Microstructural and tribological behavior of TiAlN/MoS_2-Ti coatings

A TIA1N/MoS2-Ti coating was developed to improve the tribological characteristics of a single TiAlN coating. The MoS2-Ti layer was deposited by a DC magnetron sputtering system on the hard TiAIN coated SKD-11 steel substrate. The titanium content in the MoS2-Ti layer was 11.3 at.% determined by EPMA. The surface morphology was observed by FE-SEM. The TiAlN layer exhibited excellent adhesion and hardness. However, the deposition of an MoS2-Zi layer on the TRAIN led to a significant improvement in tribological properties without affecting the adhesion to the substrate. The MoS2-Ti layer significantly decreased the friction coefficient of the TiAIN coating, and the drop was 48% after MoS2-Ti deposition. Also, the MoS2-Ti layer remarkably decreased the wear rate of the TtA1N coating.

Tribological performance of MoS2 coating on slipper pair in axial piston pump

This study investigates tribological performance of MoS2 coating on slipper pair in axial piston pump.Firstly,the MoS2 coating on the surface of slipper pair was prepared by atmospheric plasma spraying treatment technology.Secondly,the tribological characteristics of slipper pair under various working conditions were evaluated on ring-on-block tester in oil lubrication.The original and worn surfaces of the specimens were analyzed with scanning electron microscope and energy dispersive spectrometer,and then the wear morphologies of the MoS2 coatings were imaged by X-ray photoelectron spectroscopy.The experimental results showed that the friction coefficients of Cu-based materials with MoS2 coating decreased by about 0.05 at 800 N.Especially,when the external load was set to 800 N,the wear rate of the ZY331608 decreased by about 16.4%after the substrates were treated by the MoS2 coating,which exhibited excellent anti-friction and wear resistance.The formation of the MoS2 lubricating film could be classified into four stages,including the initial friction stage,anchoring stage of MoS2 on friction surface,covering stage of the sliding surface by MoS2 and the formation stage of MoS2 film.The dominating wear mechanisms of Cu-based materials with MoS2 coating were adhesive wear and abrasive wear accompanied with oxidative wear.

Investigation on MoS_2 and Graphite Coatings and Their Effects on the Tribological Properties of the Radial Spherical Plain Bearings

With constant enlargement of the application areas of the spherical plain bearings,higher quality lubrication of the bearings is required.To solve the lubricating problems of spherical plain bearings under high temperature,high vacuum,high speed,heavy loads and strong oxidation conditions,it is urgent for us to develop more excellent self-lubricating technologies.In this paper,the bonded solid lubricant coatings,which use inorganic phosphate as the binder,the mixture of MoS2 and graphite with two different weight proportions as the solid lubricant,are prepared by spraying under three different spray gun pressures.The bonding strength tests on the coatings show that the best spraying pressure is 0.2 MPa and the better mixing proportion of MoS2 to Graphite is 3：1.Then for the radial spherical plain bearings with steel/steel friction pair,after the coatings are made on the inner ring outer surfaces,the friction coefficient,the wear loss and the friction temperature of the bearings under four oscillating frequencies are investigated by a self-made tribo-tester.The test results,SEM of the worn morphologies and EDS of worn areas show that tribological properties of the bearing are obviously improved by the bonded solid lubricant coatings.When sprayed under the spray gun pressure of 0.2 MPa,the bearings have better anti-friction and anti-wear properties than those sprayed under 0.1 MPa and 0.3 MPa.Further as proved from the XPS analysis,between the coating with 3：1 mixing ratio of MoS2 to Graphite and the coating with 1：1 ratio,the former has less oxidation occurred on the surface and therefore has better tribological characteristics than the latter.This paper provides a reference to developing a new product of the radial spherical plain bearings with high bonding strength,oxidation resistance and abrasion resistance.

The influence of MoS_2 on tribology characteristic parameter of Ni60A/MoS_2 composite lubricating coating

The influence of MoS2 on the tribology characteristic parameter of Ni60A/MoS2 composite lubricating coating was researched on the UMT-2 fretting abrasion tester （USA） The result shows that with increasing content of MoS2, the hardness curve of the composite coating decreases and the trend accelerates. Under the same experimental conditions, the mass loss of plasma spray composite coating without adding MoS2 iS 1.27×10^-2 mg. When the amount of MoS2 reaches 35%, the mass loss is 0.96×10^-2 mg. It can be seen that adding MoS2 phase can improve the wear resistance, the amplitude of which is close to 30%. The friction coefficient of plasma spray composite coating without adding MoS2 is 0.23. Adding MoSz could decrease the friction coefficient of the coating and presents a downtrend. When the mass fraction is 35%, the friction coefficient is the smallest （0.13）, and the range is doubled.

Tribological Performance of MoS_2-based Coatings after Deposition and Storage in Humid Air

MoS 2-based composite coatings were deposited with the nano-compound unbalanced plasma plating technique. The effects of processing parameters and working environments on the tribological properties of the coatings were examined by the drilling experiments and XPS. The distances between substrate and Ti target, Ti content and deposition pressure were varied in order to determine the optimum conditions for producing lubricious, long-lasting MoS 2-based coatings. It is found that the tribological performance of TiN-MoS 2 coating decreases rapidly in humid air but the humid-resistant property of TiN-MoS 2/Ti coating improves evidently.It is indicated that the humid-resistantance property and the abrasion durability of MoS 2-based coatings can be enhanced markedly by adding Ti with a certain contents.

Si/MoS2及C-Si/MoS2涂层在不同湿度条件下摩擦磨损性能

为了改善传统MoS2涂层的摩擦学性能,利用中频直流磁控溅射技术在硅片和304不锈钢上沉积Si/MoS2和2种不同碳含量的C-Si/MoS2复合薄膜,利用扫描电镜(SEM)配备的EDS设备对薄膜的成分及厚度进行表征,利用真空摩擦磨损试验机(CSM)测试不同湿度条件下Si/MoS2和C-Si/MoS2的摩擦磨损性能。结果表明:2种不同碳含量的C-Si/MoS2含有相似的Si含量,Si在薄膜中以单质的形式存在;Si/MoS2薄膜随着湿度的增加,摩擦因数持续增加,同Si/MoS2薄膜相比,掺碳量49.08%(原子分数)的C-Si/MoS2薄膜摩擦性能得到优化,仅在24%湿度下摩擦因数高于纯Si/MoS2薄膜;含碳量为49.08%的C-Si/MoS2薄膜磨损程度最小,这是因为C在摩擦过程中易剪切滑移,与MoS2耦合润滑,优化了薄膜的摩擦学性能;真空下,Si/MoS2薄膜及C-Si/MoS2薄膜的磨损机制为黏着磨损,而在不同湿度条件下,由于水蒸气和氧气的作用,Si/MoS2薄膜及C-Si/MoS2薄膜均会发生氧化磨损及磨粒磨损。

Friction and Wear Behaviors of MoS_2/Zr Coated HSS in Sliding Wear and in Drilling Processes

MoS2 metal composite coatings have been successful used in dry turning, but its suitability for dry drilling has not been yet established. Therefore, it is necessary to study the friction and wear behaviors of MoS2/Zr coated HSS in sliding wear and in drilling processes. In the present study, MoS2/Zr composite coatings are deposited on the surface of W6Mo5Cr4V2 high speed steel（HSS）. Microstructural and fundamental properties of these coatings are examined. Ball-on-disc sliding wear tests on the coated discs are carried out, and the drilling performance of the coated drills is tested. Test results show that the MoS2/Zr composite coatings exhibit decreases friction coefficient to that of the uncoated HSS in sliding wear tests. Energy dispersive X-ray（EDX） analysis on the wear surface indicates that there is a transfer layer formed on the counterpart ball during sliding wear processes, which contributes to the decreasing of the friction coefficient between the sliding couple. Drilling tests indicate that the MoS2/Zr coated drills show better cutting performance compared to the uncoated HSS drills, coating delamination and abrasive are found to be the main flank and rake wear mode of the coated drills. The proposed research founds the base of the application of MoS2 metal composite coatings on dry drilling.

Surface texturing for adaptive Ag/MoS_2 solid lubricant plating

The objective of this research is to prepare specially designed surface texture on hard steel surface by electrochemical micromachining (EM) and to incorporate electroless plated Ag/MoS2 solid lubricant coating into the dimples of EM textured steel surface to effectively reduce friction and wear of steel-steel contacts. The friction and wear behavior of the Ag/MoS2 solid lubricant coating on EM textured steel surface was evaluated in relation to the size and spacing of the dimples thereon. The microstructure of as-plated Ag/MoS2 solid lubricant coating and the morphology and elemental composition of the worn coating surface and counterface steel surface were analyzed by means of optical microscopy, scanning electron microscopy, and energy dispersive spectrometry. It is found that electroless plated Ag/MoS2 coating is able to greatly reduce the friction and wear of the EM textured steel disc coupled with GCr15 steel ring, mainly because of the formation of solid self-lubricating layer on the EM textured steel surface and of transferred lubricating film on counterface steel surface. The diameter and spacing of the dimples are suggested as 500 μm for acquiring the best wear resistance of the hard steel discs after electrochemical micromachining treatment and electroless plating of Ag/MoS2 solid lubricating coating.

Molybdenum Disulfide Sheathed Carbon Nanotubes

Single and double layered MoS2-coated multiwalled carbon nanotubes (MWCNs) were successfully prepared by pyrolyzing (NH4)2MoS4-coated multiwalled carbon nanotubes in an H2 atmosphere at 900℃. MoS2-coated MWCNs would be expected to have different tribological and mechanical properties compared to MoS2, so it may have potential applications in many fields.