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A series of composite coatings (Ni60-Ti 3 SiC 2) were prepared by laser cladding on 304 stainless steel (SUS304). Then the tribological properties were investigated at room temperature (RT) and 600 °C. From the results, because of the fine-grain and dispersion strengthening caused by the presence of small-sized hard phases, the hardness of coatings was much higher than substrate. Benefiting from the addition of Ti 3 SiC 2 lubricant, the friction reduction and wear resistance were decreased greatly, especially the wear rate and friction stability were enhanced 88.9% and 61.5% respectively at the high temperature. The wear mechanisms changed from serious oxidation adhesive wear on the substrate to the slight abrasive wear under the auxiliary lubrication of oxide films and Ti 3 SiC 2 on the composite coatings. • The ternary layered ceramic MAX phase Ti 3 SiC 2 played the role of lubricant in the coating. • The hardness and tribological properties of 304 stainless steel were greatly improved. • The strengthening mechanisms of the coating with different amount of Ti 3 SiC 2 are quite different. • The formation of specific oxides has positive effects in the high-temperature tribological process. [ABSTRACT FROM AUTHOR]

The composite coatings were prepared on Ti6Al4V alloy with preplaced mixed Ni60-TiC-WS 2 powders by laser cladding. The microstructure, phase compositions and tribological properties as well as the corresponding wear mechanisms of the composite coatings at 20, 300, 600, 800 °C were analyzed systematically. The results indicate that the microhardness of the composite coatings is higher than that of the substrate. Due to the synergetic effects of the in-situ synthesized solid lubricants and hard phases, both the wear resistant and friction reducing capabilities of the composite coatings are better than that of the substrate at all experimental temperatures. With the increasing of temperature, the friction coefficients and wear rates of the composite coatings and the substrate all decrease. Moreover, when the composition of cladding powders is Ni60–16.8% TiC-23.2%WS 2 (wt%), the friction coefficients is 0.321 and wear rates are 2.9 × 10−5 mm3/Nm at 800 °C. The plastic deformation and delamination as well as oxidation wear are main wear mechanisms of the substrate at 800 °C, while the composite coatings is predominated by the oxidation wear and slight adhesive wear at 800 °C. • Main phases of the coatings are (Ni, Cr), TiS, NiS, (Ti, W)C 1 -x , TiC and Cr 7 C 3. • The coatings exhibit good wear properties at high temperatures. • The coatings with good self-lubrication in wide temperature range. • The corresponding wear mechanisms were revealed in details. [ABSTRACT FROM AUTHOR]

Highlights • Ti 5 Si 3 /Al 3 Ni 2 reinforced Al 3 Ti/NiTi composite coatings were synthesized. • The coating N2 exhibited better wear resistance than Ti6Al4V alloy. • The coating N2 showed excellent high temperature oxidation resistance. Abstract To enhance the wear resistance and elevated temperature antioxidation of Ti6Al4V alloy simultaneously, Ni-20Cr powders with the addition of Al and Si were deposited successfully on its face by laser in-situ synthesizing. The microstructure, micro-hardness, wear, elevated temperature antioxidation of composite coatings were researched. The results show that the composite coatings are mainly composed of Ti 5 Si 3 /Al 3 Ni 2 as reinforcing particles and Al 3 Ti/NiTi as intermetallic matrix, and had a metallurgical bonding with substrate. The average micro-hardness of composite coatings are 2.5–3 times higher than that of the Ti6Al4V alloy. Moreover, when the precursor composition is NiCr-40Al-20Si (wt.%), the composite coating presents a better wear resistance at room temperature (RT), which is twice higher than that of substrate because of superior hardness, strong intermetallic atomic bonding and toughness, because of the emergence of continuous dense Al 2 O 3 scales, the composite coating presents an enhanced oxidation resistance at 800 °C. [ABSTRACT FROM AUTHOR]