جستجوی مقالات مرتبط با کلیدواژه "pacvd" در نشریات گروه "مواد و متالورژی"

The purpose of this study is to investigate the microstructure and surface properties of titanium-aluminum nitride (TiAlN) nanostructured coatings produced at different deposition temperatures. The TiAlN nanostructured coatings were deposited on nitrided hot-work tool steel (H11) using pulsed direct current plasma assisted chemical vapor deposition method (DC- PACVD). The coatings were produced under the same conditions such as duty cycle, frequency and H2/Ar/N2 gas ratio at 33%, 10 kHz and 400/150/50 sccm, respectively. Also the specimens were deposited at temperatures of 470, 485, 500 and 515 °C by PACVD method. TiN coating interlayer was used to improve the adhesion strength of TiAlN coatings to the substrate. FESEM , SEM and XRD devices were used to characterize the coatings and Vickers micro-hardness and scratch test were used to evaluate the mechanical properties and adhesion strength of the coatings. The results indicated that the maximum hardness of TiAlN coating produced at 485 °C. It is attributed to various factors such as lattice parameter, crystallite size and amount of chlorine in the chemical composition of the coating. Also, due to the formation of a nanoscale- thin layer of Fe4N at the interface between the coating and the substrate at the temperatures above 500 °C, the adhesion strength of the TiAlN coating reduces. By quantitative evaluation of the adhesion of the coatings, it was found that the coating formed at the temperature of 485 °C withstands the maximum critical load (23 N) of the scratch.

In this study, titanium aluminium carbonitride (TiAlCN) ceramic coatings with different amount of Al were deposited at 350 °C on H13 hot work tool steel substrates, using pulsed-DC plasma assisted chemical vapor deposition method. Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), glancing incidence X-ray diffraction method (GIXRD), transmission electron microscopy (TEM), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) and SEM and atomic force microscopy (AFM) were applied for characterizing of the coatings. Microhardness test utilized for evaluating of microhardness of the coatings. The coatings showed a nanostructure consisted of fcc-TiAlN and hcp-AlN nanocrystalline grains and an amorphous carbon phase. Increasing the amount of Al from ~10 to ~42 at.% led to a decrease of the surface roughness of the coating from 151±49 to 88±27 nm, due to the creation of more nuclei of AlN. Coating with the less amount of Al (~10 at.%) presented the highest microhardness of about 3840 HV0.01,due to the less amount of chloride impurity and hcp-AlN phase.

In this Study, PACVD (plasma assistant chemical vapor deposition) and Arc-PVD (cathodic arc physical vapor deposition) methods were used to deposit of DLC (diamond like carbon) on St37 steel. Then, an interlayer was performed before applying the main DLC coating using arc-PVD. Field emission scanning electron microscopy, x-ray diffraction, Raman spectroscopy, energy dispersive spectroscopy, adhesion and tribological tests were performed to characterize and evaluate of coatings. Many factors are responsible for the excellent wear and mechanical behaviors of the DLC PVD coating including the presence of TiCrAlN interlayer, the fine grains (30-40 nm), hardness gradient as well as Ti and Cr carbides. These factors, also led to reach the high adhesion for this coating. The grain size of DLC PACVD coating was measured approximately 70-110 nm. In addition the thickness of arc-PVD coating was less than that of the PACVD coating which caused lower internal stress and subsequently appropriate adhesion to the substrate. The results revealed that this coating had lower hardness and adhesion to the substrate than that of the DLC PVD.