Effect of cermet substrate characteristics on the microstructure and properties of TiAlN coatings

The composition and structure of substrate materials have important influences on coating performance,especially in terms of bond-ing strength and coating hardness,which determine whether the coating can be used for a given application.In this study,a TiAlN coating is deposited on Ti(C,N)-based cermet(TC)substrates with 0wt%-20wt%WC by arc ion plating.The influence of cermet substrate characterist-ics on the structure and properties of the TiAlN coating is then researched.Results show that the TiAlN coating deposited on the TC substrate has a columnar grain structure.As WC increases,the strength ratio of I(111)/I(200)and adhesive strength of TiAlN gradually increases.In the ab-sence of WC in the substrate,the preferred orientation of the TiAlN coating is(200).As WC increases,the preferred orientation of the TiAlN coating becomes(111)and(200).Notable differences in adhesive strength between the coating and substrate could be attributed to the micro-structure and composition of the latter.Scratching results show that the adhesive strengths of the TiAlN coating on the 0wt%-20wt%WC cer-met substrate are 52-65 N.Among the coatings obtained that on the TC substrate with 15wt%WC presents the highest H/E and H3/E2,which indicates that this coating also features the best wear resistance.The failure mechanisms of the coated tools include coating peeling,adhesive wear,and abrasive wear.As the cutting speed increases,the degree of flank wear increases and the durability of the coating decreases accord-ingly.Increases in WC result in an initial decrease followed by a gradual increase in the flank wear of the coated cermet inserts.

AFM Analysis of TiN, TiAlN, and TiAlSiN Coatings Prepared by Cathodic Arc Ion Plating

The TiN, TiAlN, and TiAlSiN coatings were prepared on YT14 cutting tool surface with CAIP（cathode arc ion plating）, the surface morphologies and phases were analyzed with FESEM（field emission scanning electron microscopy）, and XRD（X-ray diffraction）, respectively, and the coating parameters such as 3D surface micro-topography, grain size, surface height, hierarchy, profile height, and power spectral density, etc, were measured with AFM（atomic force microscope）. The results show that the phases of TiN, TiAlN, and TiAlSiN coatings are TiN, TiN＋TiAlN, TiN＋Si_3N_4＋TiAlN, respectively, while the surface roughness Sa of TiN, TiAlN, and TiAlSiN coatings is 75.3, 98.9, and 42.1 nm, respectively, and the roughness depth Sk is 209, 389, and 54 nm, respectively, the sequence of average grain sizes is TiAlN〉TiN〉TiAlSiN. The surface bearing index Sbi of TiN, TiAlN, and TiAlSiN coatings is 0.884, 1.01, and 0.37, respectively, and the sequence of surface bearing capability is TiAlN〉TiN〉TiAlSiN. At the lower wavelength（102-103 nm）, the power spectral densities have a certain correlation, and the sequence of TiN〉TiAlN〉TiAlSiN, while the correlation is low at the higher wavelength（〉103 nm）.

Ti_（1－x）Al_xNPVD薄层的微结构特征和氧化行为

Recent research on microstructural characteristics and oxidation behavior of Ti(1-x)AlxN thin film were surveyed. The Ti(1-x)AlxN coatings have three different phase regions, Bl structure for lower x value, wurtzite structure for higher x value and unidentified structure for medium x value. Based upon the selective oxidation mechanism the oxidation results of Ti(1-x)AlxN thin film with different Ti/Al ratio were predicated.

Erosion behavior and failure mechanism of Ti/TiAlN multilayer coatings eroded by silica sand and glass beads

Severe erosion by hard particles is a crucial problem to engine blades when aircraft take off and land in harsh environments, especially for the developed lightweight titanium alloy components. Here, we deposited the Ti/TiAlN multilayer coatings with various cycles on Ti–6 Al–4 V substrates by a home-made hybrid multisource cathodic arc system. The effects of the silica sand and glass beads on erosion behavior of the coatings were focused. Results showed that the Ti/TiAlN multilayer coatings eroded by the silica sand exhibited the predominant "layer by layer" failure mechanism. In particular, increasing the number of cycles led to the dramatic increase in erosion rate for Ti/TiAlN multilayer coatings, due to the deterioration of their mechanical properties. Different from the silica sand case, however, the erosion rate of the coatings treated by glass beads indicated faint dependence upon the number of cycles, where the coating failure was dominated by the "piece by piece" failure mechanism. Noted that the Ti layers along with the formed interfaces enhanced the erosion resistance of the coatings, although the failure mechanisms were differently eroded by silica sand and glass beads. Meanwhile, the Ti layers and interfaces hindered the propagation of radial cracks and restrained the lateral cracks within one single TiAlN layer.