Investigation of microstructure and mechanical properties of gears produced by powder metals with steel matrix and Ni, Mo, Cu additive

In this study, spur gears are produced by powder metallurgy (P/M). Metal powders used during compaction of spur gears are iron based and the compaction of each samples are generated by different particle size of metal powders and sintered at 1120°C. These different particle size of powders are achieved by sieve analysis. Some part of the samples which are not processed by sieve analysis is sintered at 850°C, the other part is sintered based on standard process, at 1120°C. The samples sintered at different temperatures and initially not processed by sieve analysis are sectioned by wire erosion and the physical and mechanical properties of sectioned specimens are examined. Besides that, P/M spur gears are checked in greasy and dry test equipment. Before the running of P/M spur gears, they are machined for the montage of diesel pump and dry test equipment. The experiments are divided into four parts; as geometric analysis, density, surface roughness and hardness. Also, macrostructure and microstructure of P/M gears are investigated. When the experiment results are evaluated according to particle size; being positive impact while particle size increases, density also increases and porosity decreases; being negative impact, values of surface roughness increase, values of macrohardness and microhardness decrease. When the experiment results evaluated, the impact of sintering temperature are investigated, green compacts have the lowest value of surface roughness, P/M gears which sintered at 1120°C give the best results in other analyses. When the experimental results of gears sectioned by wire erosion, edging section estimated that compacted by upper punch gave the best results for geometric analysis, porosity and surface roughness. When the density is based on, middle section have the highest density values.