Papers by Keyword: Tribological Properties

Abstract: The polytetrafluoroethylene (PTFE) matrix composites reinforced by polyphenylene sulfide (PPS) fiber and poly-p-phenelenferephthalamide (PPTA) fiber were prepared by the processes of mechanical blending, compression molding and sintering. The fractured surfaces of impacting specimens were examined by scanning electron microscopy (SEM). The tribological properties of the composites were investigated on M-2000 wear tester at dry friction condition. The wear mechanism was also discussed and the wear surfaces were examined by SEM. The result indicates that fibers which diffused in PTFE matrix wind with PTFE molecule chain, and then form grid structure. The load-bearing capacity of composites can be obviously enhanced and the trend of block fragmentation’s slide is inhibited, so that the tribological properties are improved markedly. The friction coefficient of composites is reduced by adding graphite which also prevents fibers leaving. The tribological properties of PTFE matrix composites is greatly improved because of the synergistic effect between fibers and graphite, which has good prospect for low loading application.

Abstract: In this paper are presented the results of experimental studies determining the dependence of the impact of an innovative welding micro-jet method on the intensity of abrasive wear of chrome-manganese 20MnCr5. The presented method is generally used for the constructions work items matrix for the production of silicate. The results confirm that the micro-jet welding method reduces the abrasive wear intensity of about 20% compared to the steel after thermo-chemical treatment. Other parameters such as the friction coefficient and power friction show comparable value, and therefore do not have a significant impact on working conditions.

Abstract: Deposited on hot work tool steel substrate coating system composed of AlTiCrN film covered by diamond-like carbon (DLC)-based lubricant, was the subject of the studies. The AlTiCrN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. This paper provides an analysis of the microstructure, mechanical and tribological properties. Several surface sensitive techniques and methods, i.e. High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), Raman spectroscopy and ball-on-disk were used to performed study of the coating. TEM investigation shows an amorphous character of DLC layer. It was found that tested AlTiCrN layer has nanostructural character with fine crystallites. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.02-0.04. The investigated coating reveals high wear resistance. The coating demonstrated good adhesion to the substrate.

Abstract: In this study, Gamma TiAl intermetallic alloy protective coating was deposited on the surface of 5803 aluminum alloy by supersonic particles deposition. Researchers observed the surface morphology of the coating by SEM, and researched tribological properties of the substrate material and the coating by CETR friction and wear tester and Talysurf 5P-120 surface morphology tester. The results show that,the bonding mechanism of the Gamma TiAl intermetallic alloy coating and substrate is mechanical interlocking and metallurgical bonding. The abrasion mechanism of Gamma TiAl intermetallic alloy coating is abrasive Wear. The friction coefficients of the coating are all lower than 5083 alumium alloy. The friction volume of coatings reduced 36.7% than 5083 aluminum alloy with the friction loads 50N. TiAl coating has great function to anti-attrition and wearability.

Abstract: The new type of copper matrix self-lubricating composites were prepared by powder metallurgy route. The influences of milling way and content of molybdenum disulfide on composites’ microstructure and tribological properties were researched. It is found that, M_oS₂ can’t participate in the process of mechanical alloying together with graphite and copper powder. When the mass fraction of M_oS₂ increases from 0% to 10%, the coefficient of friction of composites M_oS₂-G-C_u reduces correspondingly, however the three-dimensional network structure of copper matrix was damaged seriously in sample 10% M_oS₂-G-C_u .After the wear text there will come out solid self-lubricating film on the surface of sample 5% M_oS₂-G-C_u and 10% M_oS₂-G-C_u .

Abstract: Solid phase method was adopted to prepare the graphite fluoride solid lubricant. The friction and wear properties of graphite fluoride were tested with MMW-1 vertical universal friction and wear testing machine. The phase of graphite fluoride was analyzed with infrared spectrometer. The morphology of friction surface was analyzed with the scanning electron microscope. The results show that graphite fluoride has an excellent antifriction wear-resisting property, to compare with molybdenum sulfide, the anti-friction property increased by 35%, wear resistance increased by 49%. The main wear mechanism of the test specimens are fatigue wear and adhesive wear. The solid lubrication film for graphite fluoride was formed in the friction surface.

Abstract: In this study, 5 wt. % Ti₃SnC₂/Cu composite was synthesized by hot pressed sintering, and its tribological properties against AISI52100 steel balls were investigated using a ball-on-disk wear tester. The effects of sliding speeds and applied loads on the tribological behavior of Ti₃SnC₂/Cu were studied. The results showed the wear rate of Ti₃SnC₂/Cu composite increased with the increase of applied load and decreased with increase of sliding speed. The main tribological mechanisms of Ti₃SnC₂/Cu were abrasive wear and slightly oxidative wear. The friction coefficient of Ti₃SnC₂/Cu composite was stable and much lower than that of Cu at the same conditions. The loads were effectively born by the Ti₃SnC₂ particles and the wear resistance of the matrix was obviously improved.

Abstract: The grinding liquid concentration has a great influence to its application and cost. Based on the tribological properties, viscosity, heat capacity, the research was conducted to find the performance of grinding fluid with difference concentration. Experimental results show that the grinding fluid can be chosen with low concentration in the process of cutting grinding. For the flat surface grinding and the cylindrical grinding, appropriate method is to give high grinding liquid concentration.

Abstract: Scratch tests on (001) face, doubler face and tripler face of KDP crystals are carried out at room temperature. It shows that the friction ceoffcients of different crystal faces are affected seriously by the crystal oritations, their variation periods of (001) face, doubler face and tripler face are 90^o, 180^o and 180^o, their attitudes of relative anisotropy are 50%, 43.8% and 43.8%, and all of them are less than 0.4. The scratch mechanism of KDP crystal consists of four types: elastic and plastic deformation, ploughing, microchip, and surface damage. Differences between elastic and plastic deformation and ploughing are not obvious due to the soft-brittle nature of KDP crystal.