Ramazan Yılmaz

Microstructure and mechanical properties of injection moulded Nimonic-90 superalloy parts

Abstract This study aims to determine optimum sintering and heat treatment parameters of powder injection moulded Nimonic-90 powder parts. Determination of optimum heat treatment conditions for sintered parts aimed to achieve maximum densities, and the microstructure and mechanical properties of the produced parts were characterised in sintered and heat treated conditions. Injection moulding feedstock was prepared by mixing Nimonic-90 powder with a multicomponent binder system. After moulding, the samples were subjected to a debinding process that consists of solvent and thermal steps. To determine the sintering temperatures, the debinded samples were subjected to differential scanning calorimetry analysis, and then they were sintered at various temperatures under high level vacuum. After sintering, density measurements and optical microscope examinations were performed. The highest density values were determined for the samples that were sintered at 1330°C for 3 h. Different aging treatments were performed on the samples that achieved the highest sintered density, and the microstructures and mechanical properties were then characterised. It was determined that heat treatments had a beneficial effect on the mechanical properties of the material. Though the mechanical properties of the injection moulded materials produced were lower than the wrought Nimonic-90 materials, they have superior mechanical properties compared with cast Nimonic-90 alloys.

Microstructural and wear characterization of SiC reinforced Al2O3 · TiO2 plasma coating

Purpose – The aim of this study is to present an experimental research on a Al2O3 · TiO2 plasma coating on AISI 316 stainless steel substrate with and without SiC particulate reinforcement to show how SiC particulate effect on the hardness, wear resistance and microstructure of the coating.Design/methodology/approach – The main objective of the paper is to investigate the effect of SiC particulate on the coating properties such as hardness, wear resistance and microstructure. Achieving of this purpose, harness and sliding test, surface roughness measurements were carried out. In addition to that parallel work on microstructural examination by optical microscope were also conducted. Owing to SiC particulate is harder than Al2O3 · TiO2 plasma coating, it influence hardness and tribological behavior and result in increasing in hardness values and wear resistance of the coating reinforced with SiC particulate compare with unreinforced Al2O3 · TiO2 plasma coating.Findings – This study provides experimental res...