Zhuang Daming

Effect of sulphide layers on the tribological behavior of steels under boundary lubrication conditions

Sulphide layers were prepared on the surface of AISI 1045 steel by ion sulphurization. The anti-scuffing, friction-reducing, and wear-resistant behavior of these sulphurized surfaces were investigated systematically using a ball-on-disc wear tester with engine oil as a lubricant. SEM, EDX, XPS, and AES were used to examine the morphologies and compositions of wear scars and boundary films. Sulphide layers improved anti-scuffing properties remarkably at low sliding velocities, and exhibited good friction-reducing and wear-resistant effects. During friction the sulphide layer promoted the growth of oxide, and iron sulphide could be decomposed and regenerated to form FeS again on the rubbing surface. An appropriately thick sulphide layer optimizes the sulphur-to-oxygen concentration in the boundary film resulting in the highest load-bearing capacity, and shows that thicker sulphide layers are unnecessary.

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.

Wear mechanism of ion-sulphurization layer on steel under dry conditions

Abstract Sulphide layers were made on the surface of 1045 and 52100 steels by means of low-temperature ion-sulphurization technique. The tribological properties of sulphide layers under dry conditions in air were investigated on a reciprocating tester. The friction coefficient, endurance life and width of wear scar of sulphurized surfaces were measured. The morphologies and compositions of wear scars and wear debris were analyzed by scanning electron microscopy ( SEM) + energy-dispersive X-ray spectroscopy ( EDX) . Finally, the wear mechanisms of sulphide layer were discussed. The results showed that the sulphide layer as a solid lubrication coating could adhere to the rubbing surfaces and impede the metallic contact. The friction coefficient of sulphurized surface was decreased and its wear-resistance was improved. High-hardness substrate could extend the endurance life of sulphide layer and reduce its wear. Moreover, the sulphide layer could promote the formation of oxide, which was beneficial to the shortening of running-in process.

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.

A study of the friction and wear performance of MoSx thin films produced by ion beam enhanced deposition and magnetron sputtering

Abstract MoS x thin films were deposited by ion beam enhanced deposition (IBED) and magnetron sputtering (MS) onto the surface of IBEN Si 3 N 4 and TiN thin films. The friction and wear performances of thin films and 52100 steel were compared using an SRV model reciprocating testing machine. The results showed that all MoS x films exhibit good tribological behavior. The MS MoS x thin film has better wear resistance and the IBED MoS x film has a longer wear life. The wear resistance of IBED Si 3 N 4 and TiN thin film plus MoS x film is 3–4 times and 8–20 times that of single IBED Si 3 N 4 and TiN thin films and 52100 steel respectively. The analyses indicate that the difference in friction and wear performance between the two kinds of MoS x thin film is determined by the x value of MoS x , its microstructure and the atom mixing effect at the interface.

A comparative study on the microstructure and tribological properties of Si3N4 and TiN films produced by the IBED method

Abstract The tribological properties of Si 3 N 4 and TiN thin films produced by ion beam enhanced deposition (IBED) were compared on a SRV friction and wear testing machine. The friction coefficient of all thin films shows a descending tendency with increase in load, and is lower than that of 52100 steel. All the IBED films show a much better wear resistance than 52100 steel, especially in the higher load and frequency ranges; it can reach six times that of the latter. In order to understand the reasons for their excellent properties, the microstructure, microhardness and bonding strength with the substrate were analysed by SEM, X-ray diffraction, Knoop hardness and scratching test methods separately. The results show that the TiN(1) film exhibits the best tribological properties, which are closely related with its greater hardness and bonding strength.

Structure and friction-reducing property of the sulfide layer produced by ion sulfuration

Sulfide layers with a certain thickness were made on the surface of 1045 and 52100 steels by means of the low-temperature ion sulfuration technique. Metallography, scanning electron microscope (SEM) + energy-dispersive x-ray analysis (EDX), and x-ray diffraction (XRD) were adopted to analyze the structure of sulfide layers; the tribological properties of the layers lubricated by paraffin oil were also investigated on a reciprocating tester. The results showed that sulfide layer is porous, and its structure is mainly composed of FeS, FeS2, and substrate phases. The sulfide layer possessed a remarkable friction-reducing effect; its friction coefficient was lower on average, by about 50%, than that of the surface without layer. With the increase of layer thickness, its friction coefficient was unchanged, and under low load conditions, its operational period was prolonged. Under the same experimental conditions, the operational period of sulfide layer on 52100 steel was longer than that on 1045 steel, and its friction coefficient was lower as well.Sulfide layers with a certain thickness were made on the surface of 1045 and 52100 steels by means of the low-temperature ion sulfuration technique. Metallography, scanning electron microscope (SEM) + energy-dispersive x-ray analysis (EDX), and x-ray diffraction (XRD) were adopted to analyze the structure of sulfide layers; the tribological properties of the layers lubricated by paraffin oil were also investigated on a reciprocating tester. The results showed that sulfide layer is porous, and its structure is mainly composed of FeS, FeS2, and substrate phases. The sulfide layer possessed a remarkable friction-reducing effect; its friction coefficient was lower on average, by about 50%, than that of the surface without layer. With the increase of layer thickness, its friction coefficient was unchanged, and under low load conditions, its operational period was prolonged. Under the same experimental conditions, the operational period of sulfide layer on 52100 steel was longer than that on 1045 steel, and its friction coefficient was lower as well.

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