ML22143A952

Draft Guidelines Document for Cold Spray

ML22143A952
Person / Time
Issue date:	05/23/2022
From:	Anchondo-Lopez I NRC/NRR/DNRL/NVIB
To:
Anchondo-Lopez I
Shared Package
ML22143A950	List: ML22143A951 ML22143A952
References
Download: ML22143A952 (19)

Text

THE NRC STAFF HAS PREPARED THIS DRAFT DOCUMENT AND IS RELEASING IT TO SUPPORT THE JUNE 2022, PUBLIC MEETING ON ADVANCED MANUFACTURING TECHNOLOGIES. THIS DRAFT DOCUMENT IS SUBJECT TO CHANGE AND ITS CONTENT SHOULD NOT BE INTERPRETED AS OFFICIAL AGENCY POSITIONS. SUBSEQUENT TO THE PUBLIC WEBINAR, THE NRC STAFF PLANS TO CONTINUE WORKING ON THIS DOCUMENT AND COULD INCORPORATE STAKEHOLDER FEEDBACK RECEIVED AT THE PUBLIC WEBINAR.

Draft Guidelines Document for Cold Spray

1. Introduction and Purpose When finalized, this draft guidelines document (DGD) will provide U.S. Nuclear Regulatory Commission (NRC) staff with guidelines for conducting reviews of submittals that include the use of cold spray (CS) for both non-structural and structural applications. These guidelines are based on the NRC assessment of the CS process considerations and knowledge gaps associated with using CS for nuclear applications as documented in NRC Technical Assessment of Cold Spray, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22118A090 (hereafter, NRC technical assessment), which builds on the Pacific Northwest National Laboratorys (PNNLs) technical information and gap analysis, Assessment of Cold Spray Technology for Nuclear Power Applications, (ADAMS Accession No. ML21263A107) (hereafter, PNNL TLR). This document provides CS-specific draft guidelines under Subtask 2C, Action Plan for Advanced Manufacturing Technologies (AMTs),

Revision 1, dated June 23, 2020 (ADAMS Accession No. ML19333B973), as a supplement to the AMT generic draft guidelines document, Draft AMT Review Guidelines (ADAMS Accession No. ML21074A037) (hereafter, draft generic guidelines).

The NRC staff can refer to the generic guidelines once finalized, which can assist the NRC staffs review of a submittal requesting the use of an AMT. The finalized generic guidelines along with this DGD will identify the generic and CS-specific information that could be necessary in a submittal in order for staff to perform a timely and efficient review. The NRC technical assessment is also available for additional background and technical information to support the review of a submittal.

2. Brief Description of the NRC Technical Assessment of Cold Spray The purpose of this section is to describe the NRC technical assessment of CS, which provides the technical basis for the technical review guidelines described in this DGD. The primary objective of the NRC technical assessment is to describe important CS process considerations and associated properties and performance characteristics of the CS material. Further, the technical assessment evaluates the state of knowledge and manageability associated with each key process, property, or performance topic for CS applications, and identifies relevant technical information pertaining to each topic. This DGD is intended to build on the NRC technical assessment and provide guidelines, when finalized, to the NRC staff by identifying important considerations when reviewing a submittal requesting the use of CS.

The overall impact to nuclear safety of these key topics (e.g., safety significance) is a function of component performance and the specific component application (e.g., its intended safety function). These reports do not address the impact on nuclear safety, as such an assessment would not be possible without considering the specific component application. In addition to the technical review guidelines in this document, the NRC staff should consider the specific component application and the potential for secondary consequences, such as debris generation and associated impacts, when assessing the impact to overall nuclear safety.

As discussed in the NRC technical assessment, the NRC staff assessed the knowledge gap and manageability and provided relevant technical information for each CS topic by reviewing the information and gap analysis rankings from the PNNL TLR, as well as other relevant technical information (e.g., NRC regulatory and research experience, technical meetings and conferences, codes and standards activities, Electric Power Research Institute and U.S. Department of Energy products and activities).

3. NRC Generic Guidelines for Advanced Manufacturing Technologies and Cold Spray-Specific Guidelines The finalized generic guidelines will identify the information that could be necessary in a submittal to ensure a timely and efficient review. Appendix A to the generic guidelines (ADAMS Accession No. ML21074A037) identifies the five primary topics to be addressed in a submittal:

(1) Quality Assurance (QA): process followed during the manufacture and implementation of AMTs to ensure adherence to QA requirements (e.g., Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic licensing of production and utilization facilities, Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants), established methods (e.g., commercial -grade dedication), or both (2) Process Qualification: steps taken to demonstrate that the component will be produced with characteristics that will meet the intended design requirements (3) Supplemental Testing: testing conducted to demonstrate that those material and component properties required to meet the design requirements are acceptable in the applicable service environmental conditions, and thus the performance of the component in service will be acceptable (4) Production Process Control and Verification: steps taken to ensure that each component will be produced in accordance with the qualified process and, if the production process fails to meet the qualification essential variables, the steps taken to reestablish the qualified process (5) Performance Monitoring: actions taken to provide assurance that the component will continue to meet its design requirements until the end of its intended service life Table 1 includes the key CS process considerations and associated properties and performance characteristics of the CS material outlined in the NRC technical assessment, and identifies those principal elements from Appendix A to the generic guidelines that are expected to be most commonly applicable to each of the topic areas. However, the applicable principal elements may vary on a case-by-case basis, depending on the licensees approach to demonstrating quality and safety. Therefore, this table provides an example of applicable elements and

reflects that not every element in Appendix A to the generic guidelines is applicable to every topic area listed in Table 1.

QA comprises all those planned and systematic actions necessary to provide adequate confidence that a system or component will perform satisfactorily in service. QA processes implemented during the manufacture and implementation of AMTs ensure that QA requirements (e.g., 10 CFR Part 50, Appendix B), established methods (e.g., commercial-grade dedication),

or both, have been satisfied. For AMTs, a QA program will specifically address novel or unique aspects of manufacturing or implementation specific to the AMT. Therefore, Table 1 does not explicitly include QA as a distinct column, but QA is applicable to each of the topic areas identified in the table and achieved through successful implementation of the other four Appendix A items: process qualification, supplemental testing, production process control and verification, and performance monitoring.

4. Cold Spray Technical Review Guidelines The technical review guidelines are provided in two tables. Table 2 addresses the CS process considerations. Table 3 covers properties and performance characteristics for CS materials. It is important to note that a given submittal need not address all elements of these tables but only those that are relevant for the particular application. In general, an important consideration for any nuclear application of CS is application-specific data for the proposed processing and post-processing parameters to ensure adequate CS performance in the service environment. Such data should assess properties required for the application (e.g., adhesion, corrosion resistance) and the effects of aging mechanisms (e.g., thermal aging, irradiation effects, and stress corrosion cracking [SCC]) on these properties over the intended service life.

Tables 2 and 3 provide technical review guidelines related to the CS process considerations and component performance through the following columns:

• Topic: identifies the key aspect of the CS process or property / performance characteristic outlined in the NRC technical assessment

• Key Technical Information: summarizes the key technical information documented in the NRC technical assessment for easy reference, including those specific considerations for non-structural and structural applications of CS

• Technical Review Guidelines: provides additional guidelines to support the staffs evaluation of the proposed use of CS, and ensure its adequacy, for the intended application.

Structural vs. Non-Structural Applications of Cold Spray Table 3 addresses properties and performance characteristics for both non-structural and structural applications of CS. Several topics in Table 3 are noted as being primarily applicable to structural applications of CS but may also be applicable to non-structural applications. The primary distinction between a non-structural and structural application of CS is whether the CS material will be credited with bearing structural load for the component. Data and information on structural properties and performance of CS are limited. Therefore, the information provided for structural applications of CS is subject to change based on new information becoming available as research progresses in this area.

In general, non-structural applications of CS:

• are likely to be thinner,

• do not credit the CS material for any load-bearing capacity, and

• only credit the CS material for non-structural purposes, such as corrosion mitigation or wear resistance.

Meanwhile, structural applications of CS:

• are likely to be thicker, and

• credit the CS material for load-bearing capacity such that either the CS material entirely or the CS material in conjunction with the substrate and the interface meet the full structural strength requirements.

Two specific likely applications of CS that may either be classified as structural and non-structural applications of CS are leak/flaw repair and dimensional restoration. Additional discussion to help determine if such applications are structural or non-structural follows.

Leak/flaw repair refers to the use of cold sprayed material to seal a leak or cover a surface-breaking flaw. Currently, there is limited data on this type of application and only exploratory work has been performed. CS repair of an active leak has been demonstrated as a proof-of-concept. However, qualification testing is needed to demonstrate the effectiveness of CS for leak/flaw repair and that the required structural margins have been restored, if applicable. In principle, the use of CS for leak/flaw repair may not claim structural credit for the CS materials but may still require that the CS coatings exhibit greater structural performance than for other applications such as wear resistance or corrosion protection.

Dimensional restoration refers to deposition of CS material to repair a damaged or corroded surface. CS for dimensional restoration has been done in many material systems in the defense, aerospace, and automotive sectors. Lessons learned from these applications can be transferred to nuclear applications. Most of the prior work has been performed using aluminum (Al) or nickel/chrome (Ni/Cr) alloys as the CS powder materials. Like leak / flaw repair, the use of CS for dimensional restoration may not claim structural credit for the CS material; however, such applications can include requirements for material properties such as strength and wear resistance. The determination of whether a particular application is structural or non-structural will largely be dependent on whether the CS material is needed to meet structural requirements.

Table 1. Relevant Elements from Appendix A to the Generic Guidelines Process Supplemental Production Process Performance Topic Qualification Testing Control and Verification Monitoring Factory Application and Associated Equipment X X Field Application and Associated Equipment X X Powder Quality and Processing X X Surface Preparation X X Process Parameters and Controls X X Post-processing X X Witness Specimens X X Local Geometry Impacts on Properties and Performance X X X Non-destructive Examination X X X Adhesion Strength X X Porosity X X Edge Effects X X X Corrosion / Erosion Resistance X X Wear Resistance X X SCC Resistance X X Fatigue Resistance X X Irradiation Effects on Properties and Performance X X Tensile Properties X X Initial Fracture Toughness X X Thermal Aging X X High Temperature Time-Dependent Aging Effects (e.g., X X

Creep and Creep-Fatigue)

Table 2 - Technical Review Guidelines - CS Process Considerations Topic Key Technical Information Technical Review Guidelines

• The commonly used carrier gases are helium, Process Qualification nitrogen, and air. Helium, with its low atomic weight,

• Through process qualification, the applicant should provide provides the most rapid acceleration and generally sufficient data to demonstrate that the cold sprayed materials meet achieves the best quality coatings. the intended function and requirements.

• High-pressure CS (HPCS) systems enable

• At a minimum, the process qualification should consider the high-quality CS of high-melting-point materials that following attributes:

are currently used in the nuclear power industry, such o Process pressure (i.e., high pressure or low pressure CS) as nickel-based alloys and steels. o Equipment (i.e. stationary or portable) and nozzle types

• Low-pressure CS systems are not recommended for o Delivery systems (robotic vs. manual) high-quality CS of steels, Inconel, and other

• The applicant should identify additional application-specific high-strength and high-melt-temperature materials. attributes and associated testing as appropriate.

• Properties of the cold-sprayed material and process Production Process Control and Verification Factory considerations need to be validated using equipment

• During production, the applicant should demonstrate that process Application and nozzle types that will execute the work on control and verification will maintain the essential process and mockups or witness specimens that are parameters within the qualified ranges.

Associated representative of the actual applications.

• One possible approach to demonstrate process control and Equipment

• For both factory and portable systems, coating quality verification is to test the CS process on a mock-up of the actual is influenced by many process parameters, including application to address and resolve potential issues with the CS the selection of powders and their size distributions, deposition process and verify that the desired properties can be met choice of carrier gas and temperature, nozzle design, using the equipment and nozzle types intended for the application.

and surface preparation.

• Sections 2.1.1 and 2.4.5.2 of the PNNL TLR compare field and factory applications and associated equipment in more detail.

• Figure 2.14 of the PNNL TLR shows a framework describing process implementation, including relevant process considerations and best practices for CS applications.

• The commonly used carrier gases are helium, Process Qualification nitrogen, and air. Helium, with its low atomic weight,

• Through process qualification, the applicant should provide Field provides the most rapid acceleration and generally sufficient data to demonstrate that the cold sprayed materials meet Application achieves the best quality coatings. the intended function and requirements.

and

• HPCS systems enable high-quality CS of

• At a minimum, the process qualification should consider the Associated high-melting-point materials that are currently used in following attributes:

Equipment o Process pressure (i.e., high pressure or low pressure CS)

Topic Key Technical Information Technical Review Guidelines the nuclear power industry, such as nickel-based o Equipment and nozzle types alloys and steels. o Delivery systems (robotic or manual)

• Low-pressure CS systems are not recommended for

• The applicant should identify additional application-specific high-quality CS of steels, Inconel, and other attributes and associated testing as appropriate.

high-strength and high-melt-temperature materials. Production Process Control and Verification

• Properties of the cold-sprayed material and process

• During production, the applicant should demonstrate that process considerations need to be validated using equipment control and verification will maintain the essential process and nozzle types that will execute the work on parameters within the qualified ranges.

mockups or witness specimens that are

• One possible approach to demonstrate process control and representative of the actual applications. verification is to test the CS process on a mock-up of the actual

• For both factory and portable systems, coating quality application to address and resolve potential issues with the CS is influenced by many process parameters, including deposition process and verify that the desired properties can be met the selection of powders and their size distributions, using the equipment and nozzle types intended for the application.

choice of carrier gas and temperature, nozzle design, and surface preparation.

• Sections 2.1.1 and 2.4.5.2 of the PNNL TLR compare field and factory applications and associated equipment in more detail.

• Field applications may be subject to additional constraints, such as access limitations and radiation exposure.

• Figure 2.14 of the PNNL TLR shows a framework describing process implementation, including relevant process considerations and best practices for CS applications.

• Best practices for powder processing and handling Process Qualification include sieving to control particle size, drying to avoid

• Through process qualification, the applicant should identify the clumping, and storage in inert atmosphere to avoid essential variables related to powder quality and demonstrate that oxidation and contamination. Sections 2.2.1 and controlling these variables within identified ranges will ensure Powder 2.4.5.4 of the PNNL TLR discuss these in greater reliable and adequate component properties and performance.

Quality and detail.

• At a minimum, the process qualification should consider the Processing

• The selection of the powder is application specific following essential variables for powder quality:

depending on the application requirements, such as o chemical composition, including trace elements tensile strength, corrosion resistance, wear o powder size and morphology distribution resistance, dimensional restoration, or a combination o powder flowability of these. o powder oxidation/contamination o acceptance criteria or limits for powder reuse

Topic Key Technical Information Technical Review Guidelines

• Powders should be sieved to ensure that the particle

• The applicant should identify additional specific essential variables average size and size distribution is within and their ranges as appropriate.

specifications. The presence of either large or small

• The applicant should identify methods for particle size controls and particles reduces the velocity of particles in the protocols for powder storage and handling.

stream, which in turn reduces coating properties.

• The applicant should identify methods to prevent unacceptable degradation of powders such as corrosion and oxidation of powders in storage.

Production Process Control and Verification

• The applicant can use a variety of powder quality approaches to demonstrate process control and verification, including, but not limited to, the following:

o testing final components on a sampling basis (e.g., witness specimens with demonstration of applicability) o characterizing essential variables by routine sampling after sieving powders before initial use and reuse o sieving powder prior to CS to application-specific specifications o implement procedures to prevent powder degradation

• The applicant should demonstrate that the size distribution of the powder is within the specified ranges.

• Poor surface preparation results in poor adhesion, or Process Qualification bonding, to the substrate.

• Through process qualification, the applicant should identify the

• Failure to remove oxide layers from a substrate necessary surface conditions including the necessary surface surface before CS application can negatively impact roughness and cleanliness for achieving a good quality coating.

coating performance. Cleaning procedures should not cause any damage to the surfaces

• Surface preparation examples include grit blasting, that are to be coated that may detrimentally affect CS adhesion or Surface abrasive pads, and wire brushes or wire wheels. component performance.

Preparation

• The surfaces to receive CS deposits should be Production Process Control and Verification cleaned to remove oil, grease, dirt, paint, oxides, and

• During CS application, measures should be employed to protect the other foreign material that could affect CS adhesion. surface to be coated from dust, dirt, moisture, and other

• Section 2.2.4 of the PNNL TLR discuss surface contaminants that may detrimentally affect CS adhesion.

preparation and post cleaning in more detail.

• The applicant can use a variety of post process quality testing such as adhesion testing and NDE to validate the adequacy of surface preparation practices and procedures.

Topic Key Technical Information Technical Review Guidelines

• One governing process parameter is the critical Process Qualification velocity (Vcr), defined as the velocity above which the

• The applicant should identify the essential CS process parameters particles are sufficiently plastically deformed upon and demonstrate that controlling these parameters will ensure impact and adhere to the substrate, or previous reliable, adequate, and repeatable CS properties and performance.

coating layers, as appropriate.

• The process qualification should consider application-specific

• Nozzle clogging is one of the most common problems requirements and tailor the essential CS process parameters as with the CS process and requires continuous appropriate. At a minimum, the process qualification should monitoring. Nozzle clogging reduces particle velocity, consider the following essential CS process parameters and resulting in reduced mechanical properties and controls:

increased porosity. o gas temperature and pressure

• Algorithms to flag operators at the onset of o substrate temperature preclogging conditions and record clogging conditions o powder feed rate in data logs can be developed as an automated o particle impact velocity Process quality tool. o angle of powder impact on substrate Parameters

• The primary defects in CS are caused by variations in o nozzle distance to surface and Controls process parameters, such as gas temperature, o nozzle traverse speed substrate temperature, powder size, powder oxidation

• The applicant should identify additional application-specific process or contamination, nozzle-to-surface distance, nozzle parameters as appropriate.

clogging, and powder impact angle. Production Process Control and Verification

• Process parameters such as those identified in Table

• During production, the applicant should demonstrate that process 2.2 of PNNL TLR should be implemented. control and verification will maintain the essential process parameters within the qualified ranges.

• The applicant can use a variety of approaches to demonstrate process control and verification, including, but not limited to, the following:

o witness coupons representative of the intended application can be prepared during the CS deposition and tested to confirm the quality of the as-deposited coating.

o monitor essential CS machine parameters such as gas temperature, powder velocity and nozzle traverse speed.

• For all postprocessing approaches, Process Qualification application-specific demonstration is important to

• For process qualification, the applicant should identify appropriate identify adequate heat treatment to achieve the post-processing techniques and demonstrate the intended effects of Post-desired improvements in properties. post-processing on the desired properties of the coating and the processing

• Heat-treating CS coatings is uncommon because the substrate.

as-deposited coating typically has the required

• The applicant should provide sufficient data to identify the essential mechanical properties for coating and dimensional variables related to post-processing and demonstrate that

Topic Key Technical Information Technical Review Guidelines restoration applications that dominate CS controlling these variables within identified ranges will ensure applications. Heat treatment is also typically reliable and adequate component properties and performance.

impractical for field mitigation and repair applications,

• At a minimum, the process qualification for post-processing heat which also represent a sizeable percentage of CS treatments should identify the required time vs. temperature profile, applications. including heating rate, cooling rate, hold times at specific

• Thermal postprocessing may also be complicated by temperatures, and the required environment during heat treatment.

application-specific considerations of distortion

• The applicant should identify additional application-specific post-between the CS coating and the substrate, as well as processing requirements as appropriate.

impacts of heat treatment on the substrate materials Production Process Control and Verification properties.

• During production, the applicant should demonstrate that process

• Postprocess grinding or machining may be needed control and verification will maintain the production process within for final dimensional control and blending contours. the qualified essential variable ranges for post-processing.

• The applicant can use a variety of approaches to demonstrate process control and verification, including, but not limited to, the following:

o testing final components on a sampling basis o witness specimens with demonstration of applicability o validated monitoring of post-processing parameters during heat treatment

• Table 2.3 of the PNNL TLR indicates CS property Process Qualification variables that may be important to evaluate to ensure

• The applicant should identify the material properties, microstructure, good CS performance. and other characteristics for which witness testing will be used to

• Destructive coupon tests can include appropriate demonstrate process qualification including, for example:

specimens to assess surface profiles, porosity, tensile o adhesion strength bond/yield strength, hardness, and corrosion o porosity susceptibility. Some relevant standards for testing o hardness properties of CS coatings include the following: o yield and tensile strength

- ASTM E8/E8M for tensile testing o fatigue resistance Witness

- ASTM E92 for hardness testing o fracture toughness Specimens

- ASTM D4541 for bond strength using adhesive o corrosion resistance.

pull testing

• The applicant should demonstrate how witness specimens are

- ASTM E2109 for porosity measurement representative of the end-use component in terms of microstructure and material properties.

• The applicant should discuss the witness testing program, addressing aspects such as a description of tests to be performed, associated standards used to perform testing, the acceptance criteria for each test, and the sampling frequency associated with each test.

Topic Key Technical Information Technical Review Guidelines Production Process Control and Verification

• The applicant should indicate how witness testing will be used to demonstrate that process control and verification will maintain the production process within the qualified essential variable ranges during production.

• The applicant can use a variety of witness specimen approaches to demonstrate process control and verification, including, but not limited to, the following:

o confirming that CS process parameters (e.g. gas/powder velocity, powder feed rate) remain within acceptable ranges.

o confirming required material properties and characteristics (e.g., spray thickness, adhesion strength, porosity, surface finish)

• Local geometry can impact CS process parameters Process Qualification/Production Process Control and Verification such as nozzle-to-surface distance and powder

• Through process qualification, the applicant should provide impact angle, which can affect the local sufficient data to demonstrate that local geometry impacts on microstructure and properties. material properties and microstructure will be addressed to ensure

• Geometric features such as obstructions and internal adequate CS properties and performance.

corners may be challenging to obtain necessary

• One possible approach to demonstrate process control and Local coverage and result in significant variation in coating verification is to test the CS process on a mock-up of the actual depth. application to address and resolve potential issues with geometric Geometry Impacts on

• Properties of the cold-sprayed material and process features and verify that the desired properties can be met using the Properties considerations need to be validated, most likely equipment and nozzle types intended for the application.

and through qualification on representative mockups,

• The applicant should identify additional application-specific Performance using the planned equipment and process considerations as appropriate.

parameters that will be used in the actual application. Supplemental Testing

• Witness specimens developed under conditions

• The applicant should demonstrate that the local geometry impacts representative of the areas of concern within complex on CS process will not unacceptably degrade material properties geometries could be used to assess the impacts on and performance due to in-service aging.

material properties and performance due to geometries or areas that are difficult to spray.

Topic Key Technical Information Technical Review Guidelines

• Visual testing can be used to examine the CS surface Process Qualification for imperfections such as chipping, cracking, and

• Through process qualification, the applicant should identify the flaking. Penetrant testing can also be used, but needed NDE methods and demonstrate the capability of the NDE surface roughness or porosities may obscure cracks methods to meet the application requirements. The NDE methods or other imperfections. should be capable of verifying coating properties such as porosity,

• It is expected that both ultrasonic testing (UT) and coating thickness, coating/substrate adhesion quality, detection of eddy-current testing (ET) can be used to examine the defects in CS materials, and inspection of substrate material quality of CS coatings. Surface roughness may affect through the CS coating.

the ability to inspect CS depositions. The

• The applicant should demonstrate the capability of the NDE effectiveness of these methods requires further methods to penetrate CS coating and perform any needed NDE of investigation. the substrate material.

Non-destructive

• UT and ET can penetrate CS coatings and be used to

• At a minimum, the process qualification should consider the impact inspect the underlying material. Thick coatings may of following attributes on NDE performance:

Examination present problems for inspection, particularly if they o powder and substrate materials contain porosity. o coating thickness

• It is anticipated that ET is appropriate for thin coatings o coating surface roughness (i.e., several millimeters); however, additional work o acceptance criteria should be done to verify the effective thickness limits. Production Process Control and Verification/Performance

• Cracks and lack of adhesion can be measured using Monitoring established UT methods. Understanding the

• Destructive testing of a demonstration or witness specimen limitations caused by coating porosity and thickness following NDE to validate the effectiveness of the NDE methods.

requires further investigation.

• Conduct in-service NDE to manage the integrity of CS coatings.

• Section 2.4.3.2 of the PNNL TLR discusses CS coating quality verification with NDE.

Table 3 - Technical Review Guidelines - CS Properties and Performance Characteristics for Non-Structural and Structural Applications Topic Key Technical Information Technical Review Guidelines

• Adhesion strength of 10-20 kilopounds Process Qualification/Supplemental Testing/Performance Monitoring per square inch (ksi) is common on a

• For process qualification and supplemental testing, the applicant should provide properly prepared surface, and adhesion an analysis, supported by sufficient data in representative or bounding strengths greater than 30 ksi are not environments (e.g. temperature, chemistry, stress), to show adequate adhesion uncommon for CS adhesion strength of strength of the CS material to the substrate over the intended service life.

higher strength alloys. o The corresponding analysis can demonstrate acceptable performance using

• Thick oxides and surface contamination approaches such as the following:

can significantly reduce the adhesion demonstrating adequate adhesion strength by adhesion tests strength of the CS coating. experience from previous applications of CS in similar environments Adhesion

• Adhesion strength may be limited by the using similar process and material Strength bond strength of the epoxy when NDE may be used to confirm adhesion quality.

epoxy-based adhesion tests (ASTM-C633, ASTM-D4541) are used.

The triple-lug shear testing described in MIL-J-24445A can be used to reach adhesion values not limited to epoxy strength.

• Porosity is known to adversely affect Process Qualification fatigue life, SCC, and irradiation-

• Through process qualification, the applicant should provide sufficient data to assisted SCC, though the precise demonstrate that porosity will be managed sufficiently to ensure reliable and quantitative impact depends on the adequate properties and performance of cold sprayed materials.

material and porosity characteristics

• Post-processing through heat treatment may reduce porosity, but this should be (e.g., pore frequency, pore size, pore demonstrated. Post-processing may not be feasible for field applications of CS.

Porosity morphology, total void fraction).

• At a minimum, the process qualification should consider the following key

• Porosity within a qualified process is characteristics when establishing acceptance criteria for porosity:

usually caused by nozzle clogging. o pore density Process control to monitor relevant o pore distribution (e.g., location relative to the surface) parameters such as gas pressure and o pore size flow rate should be implemented to o pore morphology detect nozzle clogging. Automated o total void fraction nozzle clogging detection could be

• The applicant should identify additional specific characteristics as appropriate.

Topic Key Technical Information Technical Review Guidelines integrated in CS equipment to ensure Supplemental Testing clogging does not happen in the field.

• The applicant should demonstrate that the porosity in cold sprayed materials will not unacceptably degrade material properties and performance due to in-service aging.

• This demonstration could be performed on a witness sample or a mock-up that is representative of, or bounds, the cold sprayed materials qualified pre-service condition, including post-processing.

• Data in representative environments are Process Qualification important to demonstrate that coating

• The applicant should provide sufficient data to demonstrate that edge effects will edge effects will not lead to be managed sufficiently to ensure that the CS materials have reliable and unacceptable increases in corrosion adequate properties and performance.

susceptibility near the edge of the CS

• Witness specimens representative of the intended application can be prepared coating.

• Edge effects due to stress concentration during CS deposition and tested to demonstrate that edge effects can be such as effects on fatigue susceptibility effectively managed.

(including thermal fatigue) and residual

• Post-processing through grinding, buffing or other blending techniques may be stress should be adequately investigated used to properly smooth the edges of a deposited coating to reduce edge to ensure sufficient performance in effects. Best practice should be followed to minimize detrimental cold work or service. residual stress effects. Any such post-processing should be demonstrated as

• Galvanic potentials can exist at part of the qualifications process.

component edges and crevices can exist Edge Effects if the edge is not properly blended. Supplemental Testing/Performance Monitoring

• Through supplemental testing and performance monitoring, the applicant should provide an analysis, supported by sufficient data in representative or bounding environments and loading conditions, to show that the edges associated with the CS coating termination retain adequate adhesion, corrosion, stress, and fatigue performance throughout the service life of the cold sprayed materials.

o The corresponding analysis can demonstrate acceptable performance by using approaches such as the following:

demonstrating edge effects will not unacceptably degrade essential properties and performance characteristics of the CS component over its intended service life.

addressing uncertainties in the data on edge effects on adhesion, corrosion, stress, and fatigue performance through, for example, conservative design assumptions, additional margins in analyses, use of surveillance programs, in-service inspection, or additional performance monitoring as appropriate

Topic Key Technical Information Technical Review Guidelines

• For corrosion resistance, the most used Supplemental Testing/Performance Monitoring coatings are forms of nickel, copper,

• Through supplemental testing and performance monitoring, the applicant should aluminum, or titanium. provide an analysis, supported by sufficient data in representative or bounding

• Short-term testing using ASTM environments, to show adequate corrosion/erosion resistance for the intended standards may be used to screen function of the CS component over the intended service life.

corrosion and erosion resistance of o The corresponding analysis can demonstrate meeting design requirements Corrosion /

material combinations in representative by using approaches such as the following:

Erosion environments. demonstrating equal or superior performance by comparison to Resistance

• Corrosion testing using representative corrosion / erosion performance for substrate materials (assuming similar test conditions may be necessary to in-service inspection frequency and methods) demonstrate the long-term behavior of addressing uncertainties in the data on corrosion / erosion and the implications to in-service performance through conservative design CS protective coatings.

assumptions, additional margins in analyses, surveillance programs, in-service inspection, or additional performance monitoring as appropriate

• CS can produce hard surfaces with Supplemental Testing/Performance Monitoring excellent wear resistance, especially

• Through supplemental testing and performance monitoring, the applicant should when blended powders with hard provide an analysis, supported by sufficient data in representative or bounding particles are used. environments, to show adequate wear resistance for the intended function of the

• CS materials generally exhibit higher CS materials over the intended service life.

hardness than those of the o The corresponding analysis can demonstrate acceptable safety margins by corresponding powders and bulk alloys using approaches such as the following:

due to the plastic deformation induced demonstrating equal or superior performance by comparison to wear Wear during deposition. The CS process performance for substrate materials Resistance parameters can be adjusted to achieve addressing uncertainties in the data on wear and the implications to in-a range of surface hardness and service performance through conservative design assumptions, additional ductility properties. margins in analyses, surveillance programs, in-service inspection, or

• Additional data on wear behavior may additional performance monitoring as appropriate be needed if new CS powders or environments with high-wear stressors will be present.

• Data in representative environments is Supplemental Testing/Performance Monitoring important to demonstrate that resistance

• Through supplemental testing and performance monitoring, the applicant should SCC to SCC will be adequate to meet provide an analysis, supported by sufficient data in representative or bounding Resistance component design requirements and environments, to show adequate SCC resistance for the intended function of the confirm the appropriateness of aging cold sprayed materials over the intended service life.

management approaches. o The corresponding analysis can demonstrate acceptable safety margins by using approaches such as the following:

Topic Key Technical Information Technical Review Guidelines

• Limited testing of CS commercially pure demonstrating equal or superior performance by comparison to SCC nickel appears to show substantial performance for substrate materials (assuming similar in-service resistance to primary water SCC, as inspection frequency and methods) discussed in Section 2.3.8 of the PNNL addressing uncertainties in the data on SCC resistance and the TLR. implications to in-service performance through conservative design

• Some qualification testing has been assumptions, additional margins in analyses, surveillance programs, in-performed using either commercially service inspection, or additional performance monitoring as appropriate pure nickel or titanium/titanium carbide to demonstrate SCC protection with various Inconel and SS substrates.

• SCC initiation prevention is likely more important in nonstructural applications due to the smaller thickness of the coatings.

• For structural applications of CS, SCC growth properties of the CS material are likely to be more important than for nonstructural applications.

• CS is expected to improve the Supplemental Testing/Performance Monitoring mechanical fatigue life of performance

• Through supplemental testing and performance monitoring, the applicant should because CS can induce compressive provide an analysis, supported by sufficient data in representative or bounding residual stresses in the coating and in environments and loading conditions, to show adequate fatigue performance the base metal directly beneath the throughout the service life of the CS component.

coating, like shot peening. o The applicant can use current fatigue management approaches supported by

• The potential for thermal fatigue due to sufficient data for the CS component to manage metal fatigue Fatigue different coefficients of thermal (e.g., cumulative usage factors, cycle counting, environmentally assisted Resistance expansion for the coating and substrate fatigue adjustment factors).

should be considered. o The corresponding analysis can demonstrate acceptable safety margins by

• Data in representative environments are using approaches such as the following:

important to demonstrate that fatigue demonstrating equal or superior performance by comparison to fatigue resistance will be adequate to meet testing for substrate materials (assuming similar in-service inspection component design requirements and frequency and methods) confirm the appropriateness of aging addressing uncertainties in the data on fatigue initiation and the management approaches. implications to in-service performance through conservative design

• Fatigue initiation prevention is likely assumptions, additional margins in analyses, surveillance programs, in-more important in nonstructural service inspection, or additional performance monitoring as appropriate

Topic Key Technical Information Technical Review Guidelines applications due to the small thickness of the coatings.

• For structural applications of CS, fatigue crack growth properties of the CS material are likely to be more important than for nonstructural applications.

• Data in representative environments are Supplemental Testing/Performance Monitoring important to demonstrate that irradiation

• Through supplemental testing and performance monitoring, the applicant should effects will not be significantly greater in provide an analysis, supported by sufficient data in representative or bounding CS materials than substrate materials environments, to show adequate performance after irradiation (including and that CS materials will be adequate irradiation-assisted SCC and loss of toughness) for the intended function of the Irradiation to meet component design requirements cold sprayed materials throughout its service life.

Effects on and to confirm the appropriateness of o The corresponding analysis can demonstrate acceptable safety margins by Properties aging management approaches. using approaches such as the following:

and

• For structural applications of CS, demonstrating equal or superior performance by comparison to irradiation Performance irradiation effects on bulk mechanical effects for substrate materials properties (e.g., tensile, toughness) of addressing uncertainties in the data on irradiation effects and the the CS material are likely to be more implications to in-service performance through conservative design important than for nonstructural assumptions, additional margins in analyses, surveillance programs, in-applications. service inspection, or additional performance monitoring as appropriate

• Data in representative environments Process Qualification/Supplemental Testing are important to demonstrate that

• For process qualification and supplemental testing, the applicant should provide tensile properties will be adequate to an analysis, supported by sufficient data in representative or bounding meet component design requirements environments, to show adequate tensile properties for the cold sprayed and confirm the appropriateness of materials.

Tensile aging management approaches. o The corresponding analysis can demonstrate acceptable safety margins Properties

• Tensile properties are primarily using approaches such as the following:

applicable to structural applications of demonstrating equal or superior performance by comparison to tensile CS. properties for substrate materials analyzing design requirements to demonstrate sufficient tensile properties for the cold sprayed material

• Data in representative environments Process Qualification/Supplemental Testing Initial are important to demonstrate that

• For process qualification and supplemental testing, the applicant should provide Fracture fracture toughness will be adequate to an analysis, supported by sufficient data in representative or bounding Toughness meet component design requirements

Topic Key Technical Information Technical Review Guidelines and confirm the appropriateness of environments, to show adequate fracture toughness for the intended function of aging management approaches. the cold sprayed material.

• For factory applications of CS on new o The corresponding analysis can demonstrate acceptable safety margins components, thermal postprocessing using approaches such as the following:

may be feasible and, with appropriate Demonstrating equal or superior performance by comparison to fracture parameters, would be expected to toughness for substrate materials improve fracture toughness. analyzing design requirements to demonstrate sufficient fracture

• Initial fracture toughness is primarily toughness for design and flaw evaluation purposes applicable to structural applications of CS.

• Data in representative environments Supplemental Testing/Performance Monitoring are important to demonstrate that

• Through supplemental testing and performance monitoring, the applicant should fracture toughness and mechanical provide an analysis, supported by sufficient data in representative or bounding properties do not unacceptably environments, to show adequate mechanical properties and fracture toughness degrade due to thermal aging and will after thermal aging throughout the service life of the cold sprayed materials.

be adequate to meet component o The corresponding analysis can demonstrate acceptable safety margins design requirements and confirm the using approaches such as the following:

appropriateness of aging management demonstrating equal or superior performance by comparison to the approaches. mechanical properties and fracture toughness after thermal aging for Thermal

• For factory applications of CS on new substrate materials Aging components, thermal postprocessing addressing uncertainties in the data on the mechanical properties and may be feasible, and with appropriate fracture toughness after thermal aging and the implications to in-service parameters would be expected to make performance through conservative design assumptions, additional material properties and performance margins in analyses, surveillance programs, in-service inspection, or more similar to conventional processed additional performance monitoring as appropriate materials.

• Thermal aging is primarily applicable to structural applications of CS.

High

• Data in representative environments Supplemental Testing/Performance Monitoring Temperature are important to demonstrate that high-

• Through supplemental testing and performance monitoring, the applicant should Time- temperature performance will be provide an analysis, supported by sufficient data in representative or bounding Dependent adequate to meet component design environments, to show adequate performance after high temperature time-Aging Effects requirements and confirm the dependent aging effects (including creep and creep-fatigue) for the intended (e.g., Creep appropriateness of aging management function of the cold sprayed materials throughout its service life.

and Creep- approaches. o The corresponding analysis can demonstrate acceptable safety margins by Fatigue) using approaches such as the following:

Topic Key Technical Information Technical Review Guidelines

• High-temperature, time-dependent demonstrating equal or superior performance by comparison to high aging effects are primarily applicable to temperature time-dependent aging effects for substrate materials structural applications of CS. addressing uncertainties in the data on high temperature time-dependent aging effects and the implications to in-service performance through conservative design assumptions, additional margins in analyses, surveillance programs, in-service inspection, or additional performance monitoring as appropriate