Papers by Author: Xin Feng

Abstract: In this paper, Cr coatings were prepared onto AISI 1045 steel substrates using medium frequency magnetic sputtering process, and were analyzed using the X-ray diffraction (XRD). Five kinds of lubricants were chosen and evaluated as lubricants for Cr coatings/AISI 52100 steel contacts at room temperature. The tribological properties of the lubricants were investigated using a ball-on-disk type UMT reciprocating friction tester. The results indicated that the 1-ethyl-3-hexylimidazolium hexafluorophosphate (L-P206) ILs has excellent friction-reducing properties, the friction coefficient kept at a relatively stable value of 0.036, however pure liquid paraffin has the lowest wear volume value. The Cr coatings using different lubricants show different tribology properties. The worn surfaces of Cr coatings were observed and analyzed using a scanning electron microscope (SEM).

Abstract: The screw motor is one kind of volume type power generator, the stator and the rotor is screw motor's core part. In this paper, cutting tool's internal stress and the distortion under the condition of milling inner helical curved surface was dissected with finite element method. Variable rule of feed engagement with changing of the processing parameter was discussed. The modal analysis of the special-purpose cutting tool was carried. To reduce the abnormal wear of special-purpose cutting tool in processing process and increase the special-purpose cutting life, the optimizing scheme was given. This research provides the theory reference for the optimized processing technological parameter.

Abstract: The friction and wear properties of the DLC coatings were evaluated while being lubricated with pure PAG, PAG containing PN and ZDDP using reciprocating ball-on-disk sliding UMT tester, respectively. The morphologies of the worn surfaces of the DLC coatings were observed using a scanning electron microscope (SEM). The results indicated that the DLC coatings exhibited better tribological properties under the lubrication of PAG containing PN or ZDDP than that of pure PAG. In addition, PN and ZDDP as additives show different tribological properties. The former offers better anti-wear ability, the latter offers better friction-reducing properties.

Abstract: The commercial greases for bearing applications should meet the requirements of the severe conditions of use (high load, low friction and low noise etc.). A kind of overbased calcium sulfonate complex greases was evaluated using an UMT-II friction tester, the commercial lithium greases as reference. The morphologies of the worn surfaces were observed using a scanning electron microscope (SEM). The results show that the overbased calcium sulfonate complex greases have stable friction coefficients as low as 0.090-0.094. At the same time, the overbased calcium sulfonate complex greases exhibited higher wear resistance than that of commercial lithium greases.

Abstract: AISI 1045 steels were laser-clad with Ni-based powder by CO2 HJ-4 coherent laser. The phase composition of the laser-cladding coating was investigated by means of X-ray diffraction (XRD). The cross-section of the cladding coating was observed using a scanning electron microscopy (SEM). The friction and wear properties of the laser cladding coatings sliding against AISI 52100 steel under the lubrication of liquid paraffin containing various anti-wear and extreme pressure additives were investigated using an Optimol SRV reciprocating motion friction and wear tester. Results showed that the laser-cladding coating considerably decreased coefficient of friction and increased wear resistance in sliding against AISI 52100 steel and attributed to the change in the hardness, phase composition of the laser-cladding coating and tribochemical reactions between the laser-cladding coating and the extreme pressure and anti-wear additives.

Abstract: In this paper, nickel coatings (on phosphor bronze substrates) were prepared using pulse electrodeposition method. The friction and wear behaviors of nanocrystalline nickel coating compared with coarse-grained nickel coating against AISI 52100 steel were investigated using l-butyl-3-octylimidazolium tetrafluoroborate ionic liquid and perfluoropolyether as a reference lubricant on reciprocating ball-on-flat UMT-2MT sliding tester. The morphologies of the worn surfaces were observed using a scanning electron microscope. The chemical states of several typical elements on the worn surfaces were examined by means of X-ray photoelectron spectroscopy. The results indicated that NC nickel coatings have better tribological properties than that of coarse-grained nickel coatings under lubricated conditions. This was partly attributed to the high hardness of the NC nickel coating and L-B408 ionic liquid formed tribochemical reaction films under NC nickel coatings.

Abstract: The friction and wear properties of AISI 52100 steel and DLC coatings were evaluated while being lubricated with silicone oil, PAO and PAG lubricants by using a reciprocating ball-on-disk sliding UMT tester. The morphologies of original surface and worn surfaces for the DLC and Ti doped DLC coatings were observed by using a scanning electron microscope. The results show that the DLC coatings have better tribological properties than AISI 52100 steel under silicone oil, PAO and PAG lubrication conditions. In addition, the DLC coatings have much better wear resistance than the AISI 52100 steel.