Effect of Vanadium Addition on the High-Temperature Friction Behavior in Nanostructured Al-Cr-V-N Films Prepared by UBMS.

In recent year, vanadium-doped tribological films have become available as possible candidates for self-lubrication at high temperatures. In this work, quaternary Al-Cr-V-N films were deposited onto silicon wafer and WC-Co substrates by an unbalanced magnetron sputtering using high purity (99.99%) CrAl2 and V targets with argon-nitrogen reactive gases. EPMA results revealed that vanadium atoms can incorporated from 0 to 13 at.% into the films. The maximum hardness value was ~32 GPa at vanadium content of 7.1 at.% in the Al-Cr-V-N films. The high-temperature tribometer was used to analysis the friction characteristics of the films with elevated temperature. As a result of the high temperature friction test after heating up to 700 °C, the average friction coefficient decreased from 0.62 to 0.35 with increasing of vanadium contents in the Al-Cr-V-N films. It is concluded that the reduction of the friction coefficient is attributed to the formation of V2O5, which is a Magnéli phase that acts as a lubrication at high temperature.

Multi-Functional Cr-Al-Ti-Si-N Nanocomposite Films Deposited on WC-Co Substrate for Cutting Tools.

Multi-functional quinary Cr-Al-Ti-Si-N thin films were deposited onto WC-Co substrates using a cathodic arc evaporation system. In this study, the influence of silicon contents on the microstructure, mechanical, tribological, and oxidation properties of Cr-Al-Ti-Si-N thin films were systematically investigated and correlated for application of cutting tools. Based on results from various analyses, the Cr-Al-Ti-Si-N films showed excellent properties including mechanical, tribological, oxidation and adhesion values compared with those of the Cr-Al-Ti-N film. The Cr-Al-Ti-Si-N films with a Si content of around 4.21 at.% exhibited the highest hardness of 45 GPa, very low friction coefficient of 0.38 at room temperature against an Inconel alloy ball and superior adhesion property (105 N). The Cr-Al-Ti-Si-N films also showed excellent oxidation resistance after annealing in the ambient air at 1000 °C. Therefore, the Cr-Al-Ti-Si(4.21 at.%)-N films could be help to improve the performance of machining and cutting tools with application of the films.

High Temperature Oxidation Behavior of Cr-Al-Si-N Nanocomposite Films Deposited by Filtered Arc Ion Plating Technique.

High temperature oxidation behavior of nanocomposite films is very important characteristics for application of machining and cutting tools. Quaternary Cr-Al-Si-N nanocomposite films with various compositions were deposited onto WC-Co and Si wafer substrates using a filtered arc ion plating technique. The composition of the films were controlled by different combinations of CrAl2 and Cr4Si composite target power in a reactive gas mixture of high purity Ar and N2 during depositions. The instrumental analyses revealed that the synthesized Cr-Al-Si-N films with Si content of 2.78 at.% were nanocomposites consisting of nano-sized crystallites (3-7 nm in dia.) and a thin layer of amorphous Si3N4 phases. The nanohardness of the Cr-Al-Si-N films exhibited the maximum values of ~42 GPa at a Si content of ~2.78 at.% due to the microstructural change to nanocomposite as well as solid-solution hardening. The Cr-Al-Si-N film shows superior result of oxidation resistance at 1050 °C for 30 min in air. Based on the XRD and GDOES analyses on the oxidized films, it could be revealed that the enrichment of Al (17.94 at.%) and Cr (26.24 at.%) elements in the film leads to form an Al2O3 and Cr2O3 layer on the Cr-Al-Si-N film surface. Therefore, in this study, the microstructural changes on the mechanical properties and oxidation behavior with various compositions in the Cr-Al-Si-N nanocomposite films were discussed and correlated with the deposition parameters.

Oxidation Behavior of Ti-Al-Si-N-O Nanocomposite Films Deposited by Filtered Arc Ion Plating Technique.

Oxidation behavior of nanocomposite films is very important characteristics for application of machining and cutting tools. In this study, Ti-Al-Si-N-O nanocomposite films were fabricated onto WC-Co and Si wafer substrates. The composition of the Ti-Al-Si-N-O films was analyzed by X-ray photo-electron spectroscope (XPS). Also X-ray diffactometer (XRD) analysis was conducted to investigate the crystallinity and phase transformation of the films. As a result of XRD, Ti-Al(18 at.%)-Si-N-O films showed the great oxidation resistance of 950 °C for 30 min in air. Based on glow discharge optical emission spectroscopy (GDOES) depth profiles, Ti-Al(18 at.%)- Si-N-O film annealed at 950 °C for 30 min shows formation of aluminum oxide layer on the film surface. On the other hand, Ti-Al(7.56 at.%)-Si-N-O film had a titanium oxide layer on the surface after annealing at 950 °C for 30 min.

Microstructure and Mechanical Properties of Functional Graded Ti-Al-Si-N-O Nanocomposite Films Deposited by Filtered Arc Ion Plating Technique.

Functional graded Ti-Al-Si-N-O nanocomposite films were deposited onto WC-Co substrate by a filtered arc ion plating system using TiAl and TiSi composite targets under N2/Ar atmosphere. XRD and XPS analyses revealed that the synthesized Ti-Al-Si-N-O films were nanocomposite consisting of nanosized (Ti, Al, Si)N crystallites embedded in an amorphous Si3N4/SiO2 matrix. The hardness of the Ti-Al-Si-N-O films exhibited the maximum hardness values of ~47 GPa at a Si content of ~5.63 at.% due to the microstructural change to a nanocomposite as well as the solid-solution hardening. Besides, Ti-Al-Si-N-O film with Si content of around 5.63 at.% also showed perfect adhesive strength value of 105.3 N. These excellent mechanical properties of Ti-Al-Si-N-O films could be help to improve the performance of machining tools and cutting tools with application of the film. A comparative study on microstructural characteristics among Ti-Al-Si-N-O films with various Si contents is reported in this paper.

Oxidation and Tribological Behavior of Ti-B-C-N-Si Nanocomposite Films Deposited by Pulsed Unbalanced Magnetron Sputtering.

Quinary Ti-B-C-N-Si nanocomposite films were deposited onto AISI 304 substrates using a pulsed d.c. magnetron sputtering system. The quinary Ti-B-C-N-Si (5 at.%) film showed excellent tribological and wear properties compared with those of the Ti-B-C-N films. The steady friction coefficient of 0.151 and a wear rate of 2 × 10-6 mm3N-1m-1 were measured for the Ti-B-C-N-Si films. The oxidation behavior of Ti-B-C-N-Si nanocomposite films was systematically investigated using X-ray diffraction (XRD), and thermal analyzer with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It is concluded that the addition of Si into the Ti-B-C-N film improved the tribological properties and oxidation resistance of the Ti-B-C-N-Si films. The improvements are due to the formation of an amorphous SiOx phase, which plays a major role in the self-lubricant tribo-layers and oxidation barrier on the film surface or in the grain boundaries, respectively.