Progress in tribological research of SiC ceramics in unlubricated sliding-A review

A review of tribological properties for boron carbide ceramics

In this work, a comparative study of diamond films consisting of alternate microcrystalline (MCD) and nanocrystalline diamond (NCD) layers is conducted Diamond films including monolayer, bilayer and multilayer diamond films are coated on cemented tungsten carbide (WC-Co) substrates by adopting a bias-enhanced hot filament chemical vapor deposition (HFCVD) technique Tribological properties of the diamond films are evaluated by using a reciprocal tribometer without lubrication Further milling tests are carried out to examine the cutting performances with sintered zirconia ceramics as workpiece comparatively In friction test against zirconia ceramics, the monolayer NCD film shows the lowest friction coefficient (0128) because of its smooth surface Also, the bilayer diamond film with surface coating of NCD layer (MNCD) and both of the multilayer diamond films exhibit good friction property while the monolayer MCD film has the largest friction coefficient (0292) The milling test demonstrates that the monolayer diamond (MCD and NCD) coated milling tools show poor tool life due to abrasive action of hard workpiece Working life of all the bilayer and multilayer diamond coated tools is enhanced, but large area shedding of coatings appears after some milling passes except the multilayer diamond film with surface coating of NCD layer (MNMN-CD) The multilayer film (MNMN-CD) presents superior machining performance and its working life increases by 3–75 times compared with the monolayer diamond coated ones

Tribological behavior and cutting performance of monolayer, bilayer and multilayer diamond coated milling tools in machining of zirconia ceramics

Influence of nanosecond laser processed surface textures on the tribological characteristics of diamond films sliding against zirconia bioceramic

Multilayer strategy and mechanical grinding for smoothing CVD diamond coated defective substrate

A novel deposition method combining hot filament chemical vapor deposition (CVD) method is proposed, with which a multilayer diamond film consisting of three layers of microcrystalline diamond (MCD) film with the gradually decreasing grain size as the number of layers increase is fabricated on silicon carbide substrate. The tribological behavior is examined on a reciprocating ball-on-plate tribometer. Meanwhile, the silicon carbide and one-layer diamond film are also conducted for comparison. The experimental results show that the friction coefficients of the silicon carbide are 0.35 and 0.40 for dry sliding against tungsten carbide and silicon nitride counterfaces, respectively. The corresponding friction coefficients of the one-layer diamond film reduce to 0.30 and 0.14, and the multilayer diamond film for these two contacts reaches to the lowest friction coefficients of 0.28 and 0.07. Moreover, the multilayer diamond film not only presents the high wear resistance, but also greatly reduces the wear rate of its counterpart as compared with the one-layer diamond film. Hence, the multilayer diamond film can be regarded as an alternative and potential technique to improve the tribological behavior of diamond film.

Tribological behavior of HFCVD multilayer diamond film on silicon carbide

The electronic and optical properties of Mn-doped 3C-SiC films are investigated by the first-principles calculation. The structure of Mn-doped 3C-SiC is modeled by substituting Mn atom for C or Si atom in 3C-SiC lattice. The results suggest that Mn-C and Mn-Si bonds can exist in the Mn-doped 3C-SiC. Mn location in 3C-SiC lattice significantly affects the crystal structure of Mn-doped 3C-SiC, and the Mn atom substitution for C or Si sites of 3C-SiC lattice can induce to the difference of indirect or direct band structure. The calculated results also show that some new impurity energy levels occur in the band gap of Mn-doped 3C-SiC, and the imaginary part of dielectric function of Mn-doped 3C-SiC shifts toward the infrared region in comparison with the primitive 3C-SiC. The adsorption spectrum of Mn-doping 3C-SiC, due to the transition of electrons between Mn 3d states, presents some new prominent peaks at low frequency. These results can further confirm Mn-doped 3C-SiC to act as a potential material for optical applications.

FIRST-PRINCIPLES STUDY OF ELECTRONIC AND OPTICAL PROPERTIES OF Mn-DOPED 3C-SiC FILMS

Interaction potential plays a vital role on the friction. Potential energy of two contacts directly determines on the friction force. However, many mathematic models proposed, always abandon the instantaneous status during sliding to devote to a weighted average over lateral force, which might miss some information about friction behavior. In this work, the relation among potential energies, separation distances of two contracts, and positions in the sliding direction are studied to evaluate the instantaneous friction characteristics. Two hydrogenated diamond surfaces are used as the examined model. The results show that a watershed between positive and negative friction forces locates at the position with the minimum adsorption energy. A rapid decrease in potential energy occurs near the 2.5 nN external force, where the friction coefficient approaches zero at each position in the sliding direction. Therefore, a novel method may be developed to greatly reduce the friction coefficient between two surfaces by adjusting the contract pressure.

Qunzhi Zhu

Papers

Tribological behavior of HFCVD multilayer diamond film on silicon carbide

FIRST-PRINCIPLES STUDY OF ELECTRONIC AND OPTICAL PROPERTIES OF Mn-DOPED 3C-SiC FILMS

Interaction potential and friction of hydrogenated diamond surfaces at the atomic scale: first-principle calculation