Microstructure and wear properties of multi ceramics reinforced metal-matrix composite coatings on Ti–6Al–4V alloy fabricated by laser surface alloying

ABSTRACT

To improve the wear resistance of titanium alloy, self-lubricating metal-matrix composite coatings reinforced by multi ceramic phases were designed and fabricated by laser surface alloying with the mixed powders of Ni, B₄C, graphite and Si₃N₄ on Ti–6Al–4V alloy. Microstructure and wear resistance of the coatings were investigated. The coatings were mainly composed of TiB₂, SiC, TiC_0.7N_0.3 and the phases containing Ni. There was residual graphite in the coatings. The average hardness of the coatings was 1385–1687 HV, equivalent to 3.7–4.5 times of the substrate. The coatings displayed superior wear resistance under dry sliding wear test condition at room temperature, compared to the substrate (over 13 times better than the substrate). The coating fabricated with the mixed powders of Ni:B₄C:C(graphite):Si₃N₄ = 1:1:1.5:0.2 (mole ratio) exhibited the best wear resistance due to the good matching relationship of the high hardness, good lubrication and certain toughness. The wear mechanism of the coatings was discussed.

KEYWORDS:

• Ti–6Al–4V
• laser surface alloying
• composite coating
• microstructure
• wear resistance

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the Major Research Development Program of Shandong Province [grant number 2016 GGX102018], P.R. China, the Natural Science Foundation of Shandong Province [grant number ZR2018MEM009], [grant number ZR2017MEM017], P.R. China, and Superior Discipline Talent Team Support Plan in Universities of Shandong Province, P.R. China.