Abstract
Ni/60WC coatings on copper substrate were placed via laser deposition (LD). A structural study was conducted using electron microscopy and a microhardness evaluation. Two body abrasive wear tests were conducted with a pin-on-plate reciprocating technique. A tool steel X12MF GOST 5960 (C-Cr-Mo-V 1.6-12-0.5-0.2) with a hardness of 63 HRC was used as a counterpart. The following results were obtained: Precipitation of the secondary carbides takes place in the thicker layers. Their hardness is lower than that of the primary carbides in the deposition (2425 HV vs. 2757 HV) because they mix with the matrix material. In the thin layers, precipitation is restricted due to a higher cooling rate. For both LD coatings, the carbide’s hardness increases compared to the initial mono-tungsten carbide (WC)-containing powder (2756 HV vs. 2200 HV). Such a high level of microhardness reflects the combined influence of a low level of thermal destruction of carbides during laser deposition and the formation of a boride-strengthening phase from the matrix powder. The thicker layer showed a higher wear resistance; weight loss was 20% lower. The changes in the thickness of the laser deposited Ni-WC coating altered its structure and wear resistance.
Highlights
Copper and its alloys are widely used as heat exchangers, conductors, mold plates for continuous casting, and the tuyeres of blast furnaces due to their excellent electric and thermal conductivity
The increased wear resistance of thick coatings can probably be associated with a lower cooling rate, which leads to the following results
There is a larger quantity of secondary carbides in thick coatings due to longer precipitation time
Summary
Copper and its alloys are widely used as heat exchangers, conductors, mold plates for continuous casting, and the tuyeres of blast furnaces due to their excellent electric and thermal conductivity. In many cases, the material’s surface must possess a high level of wear resistance. Electroplating [1], thermal spraying [2], and arc cladding [3] have been adopted. The bonding strength between the coating and the copper substrate and/or insufficient wear resistance are critical problems when using these methods. Laser cladding is useful for producing wear-resistant coating, for copper [4,5,6] due to the high specific heat input, which is significantly higher than that of arc and plasma treatments
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