TY - JOUR
T1 - Cold-Sprayed Ni-hBN Self-Lubricating Coatings
AU - Smid, I.
AU - Segall, A. E.
AU - Walia, P.
AU - Aggarwal, G.
AU - Eden, T. J.
AU - Potter, J. K.
N1 - Funding Information:
The authors thank AFRL/MLKNWright–Patterson AFB under contract FA8650-04-C-5042 for supporting this project. In addition, the authors gratefully acknowledge the assistance of Carl Hager, who helped with many aspects of this research.
PY - 2012/9
Y1 - 2012/9
N2 - Feedstock preparation strategies were explored to produce composite admixed, milled, and precoated (encapsulated) powders of nickel-hexagonal boron nitride (Ni-hBN) for cold-sprayed self-lubricating coatings. The resulting cold-sprayed coatings were then examined for microstructural homogeneity and composition, as well as bond strength, microhardness, and relevant wear behaviors. Though admixed powders were easy to prepare and economical, milled and precoated formulations provided the advantage of aiding contact between Ni and lubricant powders prior to spraying that ultimately improved deposition and properties. The maximum amount of hBN that could be effectively built into the cold-sprayed Ni coatings was approximately 6 wt%. Results of the study also indicated that the composite coatings exhibited slightly higher hardness and reduced adhesive strength relative to a baseline of pure Ni layers. Moreover, some reductions in friction and expected decreases in bond strength and lubricant uniformity were observed when more than 4 wt% of lubricant was retained in the coatings. Given these findings, the most promising path to improve the amount, uniformity, and influence of the lubricant may be to encapsulate smaller particles with thicker levels of Ni to "trick" the composite particle to bond as pure Ni.
AB - Feedstock preparation strategies were explored to produce composite admixed, milled, and precoated (encapsulated) powders of nickel-hexagonal boron nitride (Ni-hBN) for cold-sprayed self-lubricating coatings. The resulting cold-sprayed coatings were then examined for microstructural homogeneity and composition, as well as bond strength, microhardness, and relevant wear behaviors. Though admixed powders were easy to prepare and economical, milled and precoated formulations provided the advantage of aiding contact between Ni and lubricant powders prior to spraying that ultimately improved deposition and properties. The maximum amount of hBN that could be effectively built into the cold-sprayed Ni coatings was approximately 6 wt%. Results of the study also indicated that the composite coatings exhibited slightly higher hardness and reduced adhesive strength relative to a baseline of pure Ni layers. Moreover, some reductions in friction and expected decreases in bond strength and lubricant uniformity were observed when more than 4 wt% of lubricant was retained in the coatings. Given these findings, the most promising path to improve the amount, uniformity, and influence of the lubricant may be to encapsulate smaller particles with thicker levels of Ni to "trick" the composite particle to bond as pure Ni.
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U2 - 10.1080/10402004.2012.686085
DO - 10.1080/10402004.2012.686085
M3 - Article
AN - SCOPUS:84865282901
SN - 1040-2004
VL - 55
SP - 599
EP - 605
JO - Tribology Transactions
JF - Tribology Transactions
IS - 5
ER -