MIL-STD-3021 (W/ CHANGE-2), DEPARTMENT OF DEFENSE MANUFACTURING PROCESS STANDARD: MATERIALS DEPOSITION, COLD SPRAY (04-MAR-2015)

MIL-STD-3021 (W/ CHANGE-2), DEPARTMENT OF DEFENSE MANUFACTURING PROCESS STANDARD: MATERIALS DEPOSITION, COLD SPRAY (04-MAR-2015)., The procedures covered by this standard are intended to ensure that cold spray operations, either manual or automated, meet prescribed requirements. This standard ensures that cold spray operations are repeatable and consistent. However, additional qualification requirements may be required based on each specific application. Therefore, for structural applications and other applications that are considered critical - (safety critical or FOD critical), a qualification plan shall be provided by the Cognizant Engineering Authority (CEA) (see 3.13) and shall follow the recommendations specified in Appendix A and shall be specified in the contract or purchase order (see 6.2). The purpose of this standard is to develop the manufacturing process controls for a cold spray operation utilizing a high-velocity jet of solid-phase particles. The jet temperatures are below the melting thresholds of many engineering materials. This allows the process to be used to apply deposits on a wide variety of substrates, such as, alloys, ceramics, and plastics, as well as to produce bulk materials and near-net shaped parts. The uniqueness of cold spray lies in its ability to produce a coating, provide dimensional restoration or even produce a near-net shaped part at temperatures well below the melting point of the powders being applied, thereby avoiding or minimizing many deleterious high temperature reactions which are characteristics of typical thermal spray processes. This ensures that the input powder materials do not experience any grain growth, oxidation or phase changes when deposited. It is this characteristic of cold spray that makes it attractive as a method for coatings or for dimensional restoration, and/or the production of bulk materials or near-net shaped, while retaining their own unique material properties. This standard is required because the cold spray deposition process has significant differences from thermal spray coating technologies such as high velocity oxy-fuel (HVOF), detonation gun, plasma spray, flame spray, and arc spray. These process differences result in application criteria, process equipment, and operating parameters that are considerably different than previously documented processes. The objective is to enable the application of Cold Spray Deposition with the success of the aforementioned processes when properly applied.