Wang Haidou

The comparison on tribological properties of ion sulfuration steels under oil lubrication

The method of low temperature ion sulfuration was utilized to treat three kinds of steel, high-speed steel (M2), die steel (L6) and plain carbon steel (1045). The iron sulfide (FeS), with 10 μm thickness, were produced on the surfaces of the three steels. The tribological properties of the sulfide layers were investigated on a ball-on-disc friction and wear test rig of QP-100 model under oil lubrication. Scanning Electron Microscopes (SEM) equipped with EDX and X-ray Diffraction (XRD) were employed to analyze the morphologies of cross-section and wear scar of sulfide layers, as well as the surface phase structures. XPS was used to detect the valence states of boundary lubrication films of worn surfaces. It can be seen that the surfaces of sulfide layers were loose and uneven, formed randomly by nano-scale sulfide grains. The results showed that the tribological properties of all sulfurized steels were improved remarkably. The tribological properties can be ranked by the order from high to low as high-speed steel-die steel-plain carbon steel. The differences of tribological properties of different steels were mainly determined in hardness, microstructure and corrosion resistance of substrate.

Comparison of the tribological properties of an ion sulfurized coating and a plasma sprayed FeS coating

The microstructures and tribological behaviors of ferrous sulfide solid lubrication coatings prepared by low temperature ion sulfuration and plasma sprayed techniques were investigated against the 52 100 steel balls. The friction and wear tests were performed with different parameters of the time and velocity under oil lubrication. The results demonstrated the influence of the coating microstructures on the frictional and wear behaviors. The friction-reduction and were-resistance of ion sulfurized coating were better than that of plasma sprayed FeS coating, however, the anti-scuffing behavior of the latter coating was better than that of the former. The difference of the tribological properties of two coatings can be attributed to their different forming mechanisms and microstructures. SEM equipped with EDX and XRD were employed to analyze the morphologies and phase structures. The scratching apparatus was utilized to measure the bonding strength between coatings and substrate.

Characterization and anti-friction on the solid lubrication MoS2 film prepared by chemical reaction technique

Abstract To develop a new way to produce the molybdenum disulfide (MoS2) solid lubrication film, the following two-step chemical reaction technique was attempted. Firstly, a Mo film was prepared by multi-arc ion plating technique, and secondly the Mo film was sulfurized by a low temperature ion sulfuration technique to obtain the MoS2 solid lubrication film. This MoS2 film was a composite film consisted of MoS2 and Mo. The lubricant MoS2 is dominant in the surface and metal Mo is dominant in the deep layer. It is an ideal frictional surface. The tribological properties showed that the solid lubrication MoS2 film possessed an excellent anti-friction property.

Comparative Investigation on Tribological Properties of Ion-Sulfuration Layers Under Dry Friction

Four kinds of steel, including high-speed steel (M2), die steel (L6), stainless steel (420) and plain carbon steel (1045), were treated by low-temperature ion sulfuration. Sulfide layers, dominated by the FeS phase, were produced on the surfaces of the four steels. The tribological properties of sulfide layers were investigated on a block-on-ring test rig under dry friction conditions. The results showed that the tribological properties of all sulfurized steels were remarkably improved. The tribological properties decreased in the order of high-speed steel—die steel—1045 steel—stainless steel. The hardness, microstructure and corrosion resistance of the substrate determined the differences in the tribological properties of different steels.

Excellent vacuum tribological properties of Pb/PbS film deposited by RF magnetron sputtering and ion sulfurizing.

Soft metal Pb film of 3 μm in thickness was deposited on AISI 440C steel by RF magnetron sputtering, and then some of the Pb film samples were treated by low-temperature ion sulfurizing (LTIS) and formed Pb/PbS composite film. Tribological properties of the Pb and Pb/PbS films were tested contrastively in vacuum and air condition using a self-developed tribometer (model of MSTS-1). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to analyze the microstructure and chemical construction of the films and their worn surfaces. The results show that a mass of Pb was changed to PbS during the process of LTIS. In air condition, owing to the severe oxidation effect, pure Pb film showed relatively high friction coefficients (0.6), and Pb/PbS composite film also lost its friction-reduction property after sliding for a short time. In a vacuum, the average friction coefficients of Pb film were about 0.1, but the friction coefficient curve fluctuated obviously. And the Pb/PbS composite film exhibited excellent tribological properties in vacuum condition. Its friction coefficients keep stable at a low value of about 0.07 for a long time. If takes the value of friction coefficients exceeding 0.2 continuously as a criterion of lubrication failure, the sliding friction life of Pb/PbS film was as long as 3.2 × 10(5) r, which is 8 times of that of the Pb film. It can be concluded that the Pb/PbS film has excellent vacuum tribological properties and important foreground for applying in space solid lubrication related fields.

Study on tribological properties of iron sulfide coatings prepared by a sol-gel method

The methods of surface chemical heat treatment, such as low temperature electrolysis sulfuration and salt bath sulfuration or low temperature ion sulfuration [1–4], are usually adopted to prepare FeS solid lubrication coatings, which possess good anti-friction properties. But these methods are all relatively complicated. As a wet chemosynthesis method, the sol-gel method possesses a lot of advantages. The facility required is simple, the process is easy to control and the purity and homogeneity are high. The method has been extensively used to prepare wear-resistance coatings [5–8]. But as yet the research results, using the method to prepare anti-friction coatings, have not been reported. The authors prepared the FeS solid lubrication coatings by a sol-gel method, besides investigated their tribological properties. The substrate material was 1045 steel (AISI). It was heat-treated by quenching and low temperature tempering, the hardness was HRC55 and the surface roughness Ra was 3.2 μm. The powder size of FeS and zinc was all about 10 μm. The volume of the solvent, patented product (ZM-1 model), was 500 ml. The total weight of the solute, both FeS and zinc powder, was 100 g. The solvent and solute were mixed and stirred evenly for 15 min to form the sol. In the sol, FeS was used as solid lubricant and Zn was used to disperse evenly the FeS powder and enhance the wet ability of FeS powder to the substrate. To compare the difference of their tribological properties, four kinds of sol with different FeS contents were prepared. The FeS contents were 10 g, 20 g, 30 g and 40 g respectively. As a correspondence the zinc contents were 90 g, 80 g, 70 g and 60 g respectively. A special equipment was utilized to spray the sol homogeneously onto the surfaces of 1045 steel about 500 μm thick. These coatings were dried in an insulation can (100 ◦C). Friction and wear tests were carried out on a ball-ondisc tester (QP-100 Model). The upper samples were 52100 steel ball with diameter 12.7 mm and hardness of 770 HV. The lower samples were the 1045 steel discs prepared with the FeS coatings, with dimensions of φ 60 × 5 mm. All tests were carried out at the condition of room temperature and atmospheric environment, lubricated with No. 40 lubrication oil (no additives). The

Microstructure and Wear Resistance of FeCrBSi Plasma-Sprayed Coating Remelted by Gas Tungsten Arc Welding Process

Herein, an FeCrBSi coating was fabricated via plasma spray on AISI1045 steel, and subsequently, a gas tungsten arc welding (GTA) process was employed to remelt the coating. The microstructure, microhardness, fracture toughness and surface roughness of the coating before and after remelting were investigated, as well as the wear resistance was tested by a UMT-3-type sliding wear apparatus. The results showed that, upon remelting, most defects in the as-sprayed coating were effectively eliminated, the surface roughness decreased by 43%, and the coating–substrate interface bonding changed from mechanical to metallurgical. The phase composition of the as-sprayed coating was primarily α-Fe and a small amount of hard Fe3B phase, while the remelted coating consisted of α-Fe and (Fe,Cr)23C6 and a small quantity of CrB. In addition, remelting the coating was found to induce a 287.6% increase in the fracture toughness, a 33.4% increase in the average microhardness, and a 47.5% decrease in the wear volume, while the failure mechanism changed from abrasive wear to fatigue wear upon remelting. Therefore, GTA remelting of plasma-sprayed coating was found to be a feasible method to obtain a coating with good wear resistance.

A New Method of Critical Failure Monitoring for the Heterogeneity Material Friction Welding Specimens Applying Multiple Physical Signals

Abstract Fatigue fracture is a common failure mode for dissimilar materials friction welded components. To reduce the major accidents caused by sudden fracture of friction welded parts, the present paper discussed the feasibility of the combined usage of electric resistance (ER), infrared thermograph (IRT) and acoustic emission (AE) to monitor the critical fatigue damage from the perspectives of energy dissipation and micro defects evolution. The study found that three kinds of signal could be acquired synchronously. They are non-interfering and mutual support. After entering the critical fracture stage, there exists a good mapping relationship between ER and the AE amplitude and energy for the specimens of abnormal and normal fracture. They all can be regarded as the parameters of monitoring critical failure. Although IRT is usually used to predict the fatigue limit of materials, the rapid temperature rising stage may not always be obvious near the fracture. Compared with the single signal monitoring, multi-information fusion has the higher credibility, which is beneficial to increase the service safety and reliability of friction welding parts.