iTSSe TSS ADVANCED MATERIALS & PROCESSES | APRIL 2024 39 iTSSe TSS substrate plate using the spherical pure aluminum powder, which provided increased interfacial mechanical anchoring. Additionally, due to the agglomerated nature of the irregular nickel powder material, nozzle clogging, poor feeding, and irregular deposition were encountered. These concerns were eliminated by using the spherical nickel powder geometry. Table 2 shows the conducted tests and sprayed/tested layer combinations. All tested combinations were successful except for the Ti64 powder deposition on a cold spray zinc underlayer, which led to coating delamination and partial erosion of the zinc coating. To solve this issue, spherical aluminum was deposited as an intermediate layer onto the zinc coating prior to deposition of Ti64. Cells highlighted in blue show the material combinations that were subsequently chosen to properly replicate the color palette of the photograph. The use of stainless steel masks with different slit geometry and size influences the gas flow near the gap edges and subsequently the particle trajectory prior to deposition. This is further accentuated with the increase of mask-to-target surface distance leading to edge blurring of FEATURE 10 TABLE 1 — SPRAY PROCESS PARAMETERS Powder material Zinc Aluminum Ti64 Steel Nickel Nickel blend Gas pressure, MPa 5.17 5 6.5 6.5 6.5 5.17 Gas temperature, °C 300 450 950 950 950 300 Gun traverse velocity, mm/s 200 200-300 300 300 110 100 Gun step size, mm 1 1-1.5 1-1.5 1 1 1 Powder feed rate, g/min 21-25 18-22 25-36 14-31 20 9-10 Particle velocity, m/s 439-445 548-560 560-575 669-681 617 569-574 Gun standoff distance, mm 30 30 30 30 30 30 Nozzle material PBI PBI SiC SiC SiC SiC TABLE 2 — MATERIALS DEPOSITION MAPPING (✓: SUCCESSFUL, ✗: UNSUCCESSFUL) Powder target Zinc Aluminum Ti64 Steel Nickel Nickel blend Grit blasted Al6061* ✓ ✓ ✗ N/T N/T ✓ CS Zinc ✓ ✓ ✗ ✗ ✓ N/T CS Aluminum ✓ ✓ ✓ ✓ ✓ ✓ CS Ti64 ✓ N/T ✓ ✓ ✓ ✓ CS Steel ✓ ✓ N/T ✓ N/T ✓ CS Nickel ✓ N/T N/T N/T ✓ CS Nickel blend ✓ N/T N/T N/T N/T ✓ *Deposition made directly on surface of grit blasted treated substrate material. N/T: Not tested. Fig. 4 — Final cold sprayed crinoid piece. A key is provided to easily match as-deposited coating color to powder material.
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