Structure and properties of X150CrMo12 steel after PVDM-R by magnetron deposition of chromium nitride coatings with next heat treatment

摘要

The CrN coatings have been deposited on X150CrMol2 steel substrates by sputtering of a sintered chromium target at metallizing temperatures T_s, ranging between 450 and 850 deg C and bias voltage U_s, ranging from 0 to -200 V by the method of "Plasma Vacuum Diffusive Metallizing-Reactive scheme" (PVDM-R) in a single-chamber vacuum furnace with a graphite heater and a heat-isolative chamber, made of carbon wool. The method is based on the diffusive interaction between the substrate and condensate, transforming the condensate into a diffusive coating with or without a residual condensate, during the metallizing. The covered samples are hardened at temperature 1020 + - 10 deg C and tempered at 200 deg C in vacuum. The kinetics and mechanism of the structure forming of the coatings are investigated. The chemical and phase composition of the coatings, the lattice parameter and texture coefficient are determined by XRD and GDOES analyses. Their micro-hardness and Young's modulus also have been investigated. The microstructure and the type of the coatings before and after heat treatment have been determined. It is determined that with pure chromium or ferro-chromium target for time 60 min is possible with previously or accompanied deposition of condensate on X150CrMol2 steel substrates (by direct or indirect process) and next vacuum heating treatment are forming chromium-carbide or chromium-nitride vacuum-diffusion coating with K_(DC) = 1 with thickness, which are equal to the both ranges, which have practical importance: 4-8 mum or 10-20 mum. It is concluded that the plasma-vacuum deposition process of vacuum condensates, built only of CrN on the steel X150CrMol2 or another steel of this group, cannot be used as a preliminary process, because the vacuum heat treatment (hardening and tempering) change the type of the coverage from vacuum coating to vacuum-diffusive coating with changing phase composition..