Thermal transport and tribological properties of nanogreases for metal-mechanic applications

• 1946 - First reports of nickel electroless process [000] • Presently, deposits of Ni−P: (W, Mo, Co) and Ni−B are used in automotive, chemical, aerospace, oil & gas, electronic and textile fields as well as to improve medical instrumentation [1–4] • Two commercial processes to deposit Ni−B electroless coaLngs: one uses borohydride and the other dimethylamine borane (DMAB) as the reducing agents. The structural characteristics idenLfied in the Ni−B coaLngs depend on the B content: a) if content is < 2wt.%, microstructure consists of a solid solution of boron into microcrystalline nickel with columnar structure; b) if content is between 2 and 6wt.% a mixture of microcrystalline and amorphous phases are formed, c) if content is ~ 6wt.% the coating becomes totally amorphous. •With thermal treatments hardness on Ni−B coaLngs can be similar to that of hard chromium with high wear resistance. The only reported disadvantage is a corrosion resistance slightly smaller than Ni−P alloys [5-9] •Heat treatment improves hardness and the adhesion of Ni–B deposited on steel [10] • Further improving the electroless Ni-B coating conditions are compared in wear tests versus hard chromium, electroless Ni-P, cubic boron nitride, and titanium nitride, reporting lower wear and a lower COF [7,11–14] •In previous research, electroless Ni-B baths are usually prepared with more than four reagents, and in a great majority they use heavy metal salts (Pb and Ta) as a bath stabilizer. • Health regulations and environmental these last salts are being banned. •In this work we use a bath of four components, easy to control and relatively low temperature (65°C), no stabilizers based on heavy metal salts are used, and the bath is very stable.