Nickel alloys and composites are interesting engineering materials as a result of a combination of mechanical, corrosion and wear resistance at service temperatures that exceed those of steels and steel-based materials. The present study aimed at sintering Ni-graphite composites from NiO-SiC mixtures and investigate the in-situ formation of graphite. NiO powders were mixed with SiC (0, 3, 5 and 10 wt.%) and attrition-milled during 1 h. The mixtures were then granulated using 1.5 wt.% paraffin in hexane solution and uniaxially pressed under 400 MPa. The cylindrical pellets were then sintered at 1200 ºC. The sintered materials were characterized by density measurements, dilatometric and microstructural analyses, as well as Vickers microhardness. The results showed that Ni-graphite composites were successfully produced from NiO-SiC mixtures with full reduction of NiO and dissociation of SiC to form a Ni-Si matrix and graphite nodules. mechanical steelbased steel based Nigraphite Ni NiOSiC insitu situ 0, 0 (0 3 wt attritionmilled attrition milled h 15 1. wt. 40 MPa 120 ºC measurements analyses microhardness NiSi Si nodules ( 4 12

The objective of the present work was to study the effect of heat treatments in the microstructure, graphite nodules and mechanical properties of self-lubricating steels, to achieve this, self-lubricating steels (Fe + 0.45C + 4Ni + 1Mo %wt) and additions of 2 and 3 %wt SiC were fabricated. They were consequently heat treated in 3 different conditions: martempering at 180 °C and tempering at 530 °C and 300 °C respectively and austempering at 300 °C. Hardness, yield strength, tensile strength and work hardening behavior were studied in as-sintered and heat-treated samples. The microstructure was analyzed by optical microscopy, scanning electron microscopy, Raman spectroscopy and micro-hardness. The transformation temperatures were determined using dilatometric tests. Results show that the presence of dissolved Si in the matrix due to SiC dissociation notably affects the morphology of the microstructure and transformation temperatures also affecting post heat treatment mechanical properties. The structure of graphite nodules produced by SiC dissociation is nott significantly affected by the heat treatments.

When multifunctional surface engineering processes that combine purpose-oriented phases are applied to soft substrates, a combination of high wear resistance, high load support and low coefficients of friction can be achieved. In this study, the effects of different nitrided layers on the tribological behaviour of a diamond-like carbon (DLC) film deposited on a SAE 1040 steel were investigated. The nitriding was carried out under different temperatures and gas mixtures to create three distinct nitrided layers: two compound layers with predominant ε and γ' phases and a diffusion layer. All of the surfaces were then coated with DLC deposited via plasma-enhanced chemical vapour deposition (PECVD). The tribological tests indicated that the best performance was achieved for a specific combination of hardness, surface roughness and nitride type. The best load-bearing capacity between the DLC coating and the soft substrate was achieved when the nitrided layer was primarily a diffusion layer.

In this work, 17-4PH stainless steel parts processed in a Plasma Assisted Debinding and Sintering (PADS) furnace were characterised in terms of microstructure, final density, microhardness, carbon content and tensile behaviour. To determine whether these properties were satisfactory, the same characterisation procedure was conducted on the parts processed by conventional batch furnaces that are normally employed in Metal Injection Moulding industrial plants. The properties were in good agreement, and only slight differences like an extremely low carbon content (0.003% w/o) were observed. It has been seen that not only economical advances but also intricate materials with suitable responses may be obtained using PADS.