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This paper aims to investigate the temperature and wear properties of vertical ball screws and to discuss the surface design of ball screws in industrial applications.

The energy equation of the screw surface considering the frictional heat was established to verify the surface temperature of the ball screw. X-ray diffraction was used to examine the micro-contact temperature between the ball and screw. Debris size and density were examined to investigate wear properties of ball screws and to study the relationship of wear debris and temperature.

First, the main energy source for the surface temperature of high speed vertical ball screws is derived from friction force between ball and screw. Second, the temperature rise between the ball and screw has great relevance with wear debris concentration. Third, the surface temperature of the screw is higher than between the nut and ball for high speed vertical ball screws due to high convection heat transfer. The contact temperature of the nut near the flange is smaller than that of the nut away from the flange end due to the high contact load and thermal conduction. Finally, correlation of particle size and surface roughness value for vertical ball screws was established, and its effects on contact temperature were studied. The theoretical analysis and experiments will help to characterize the design and manufacture of vertical ball screws.

The surface temperature and micro-contact temperature analytical model were established to study the ball screw design. Based on the surface-particle micro-contact temperature balance, the optimal range of surface roughness was designed for vertical ball screws, considering the wear debris and micro-contact temperature.

This paper aims to investigate the tribology, corrosion resistance and biocompatibility of high-temperature gas-nitrided Ti6Al4V alloy.

The tribological properties were studied by reciprocating wear tester. The corrosion resistance was evaluated by using potentiodynamic polarization test. The purified mouse leukaemic monocyte macrophage cells are used to investigate the biocompatibility.

The results show that the nitriding treatment leads to a significant improvement in the hardness and tribological properties of Ti6Al4V alloy. Specifically, compared to untreated Ti6Al4V, the hardness increases from 3.24 to 9.02 GPa, while the wear rate reduces by 12.5 times in sliding against a Ti6Al4V cylinder and 19.6 times in sliding against a Si3N4 ball. Furthermore, the nitriding treatment yields an improved corrosion resistance and a biocompatibility similar to that of untreated Ti6Al4V.

The nitrided Ti6Al4V alloy is an ideal material for the fabrication of load-bearing artificial implants.

This paper aims to develop an electrochemical abrasive jet machining (ECAJM) technology to investigate the surface machining effect of Ti-6Al-4V alloy.

First, the ECAJM equipment was set up, and a series of experiments for the surface machining of Ti-6Al-4V alloy was performed.

The experimental results show that the flowing abrasives of 0.05 Wt.% can effectively remove the TiO₂ oxide film of Ti-6Al-4V alloy surface. In addition, the flowing abrasives produce cutting machining effect on the surface of titanium aluminum alloy, and the oxide film can be removed effectively. For the case of machining pressure of 0.4 Mpa and machining gap of 0.4 mm, the processing efficiency can be achieved up to 20 µm/s.

Under different machining pressure, the flowing abrasive with high kinetic energy impacting the Ti-6Al-4V alloy surface and the oxide film produced from the electrolytic reaction process can be removed effectively, thereby enhancing the efficiency of electrochemical machining process.

Velocity slipping model, based on the stratification theory (the film in inflatable support area of aerostatic guide way was divided into near wall layer, thin layer and continuous flow layer in the direction of height), was established, and the model was combined with viscosity changes in each layer.

Simulated and analyzed by LAMMPS and two-dimensional molecular dynamics method, some relevant conclusions were drawn.

At a high temperature, viscosity is low, velocity slipping is large and velocity gaps in near-wall layer and thin layer are large. When the temperature is constant, the dimensionless slipping length and Kn number are linear.

The effect of the equivalent viscosity on gas slipping model is proposed. viscosity is smaller, gas velocity slipping is greater, temperature is higher, gas velocity slipping is greater, velocity gap of near wall layer and thin layer is larger. When the temperature is constant, the dimensionless slipping length ls and Kn number are linear.

The global model of lubricating film velocity slipping between plates was established, and mathematical expression of slipping model in each layer, based on the stratification theory, was presented.

The main aim of this paper was to study the self-lubricating behavior and failure mechanism of silver-rich solid film for in-depth analyzing of the friction and wear property of TiAl-10 wt. per cent Ag self-lubricating composite.

The friction and wear property of TiAl-10 wt. per cent Ag self-lubricating composite sliding against Si3N4 ball was tested under the testing conditions of ball-on-disk wear system. Field emission scanning electron microscopy and electron probe microanalyzer were used to analyze the surface morphology of silver-rich solid film. The main element contents were tested by energy dispersive spectroscopy. Silver phase on wear scar could be well identified using X-ray photo-electron spectroscopy. The theory calculation of shearing stress on wear scar was executed to discuss the local failure mechanism of silver-rich solid film. The lubricating role of silver was also discussed to analyze the anti-friction and anti-wear behavior of silver-rich solid film.

The friction coefficients and wear rates of TASC gradually reduced at 0-65 min, and approached to small values (0.31 in friction coefficient and 3.10×104 mm3N-1m-1 in wear rate) at 65-75 min. The excellent friction and wear behavior of TASC was mainly attributed to the lubricating property of silver-rich film at 65-75 min. At 12→20 N, surface shearing stress increased up to 146.31 MPa, and exceeded more than the shearing strength (125 MPa) of silver-rich film, which caused the propagating of fatigue crack and the destroying of silver-rich film, leading to high friction and severe wear.

It is important that the self-lubricating behavior and local failure of solid film is explored for further understanding the friction and wear property of TiAl alloys.

The purpose of this paper is to study the influence of friction on static and dynamic characteristics, as well as the strength and lifetime of a flexible three-axes computer numerical control (CNC) machine tool.

The machine tool is first modeled by using finite element method to analyze static structure with frictionless surface-to-surface contact type. Because the machine tool structure is becoming more and more sophisticated over time, the significant influence of contact conditions between structural elements on the dynamic characteristics of the whole structure must be considered. To examine the dynamic effects caused by inertia forces and displacement of moving bodies on contact stress, the coefficient of friction between two contact bodies is added to perform dynamic simulation and compare the results with the static analysis results.

Distribution of stress and contact forces in solid-flexible contact is also studied by using the fundamental dynamic characteristics of a bushing joint.

Finally, the influence of dynamic structure, cutting conditions and material properties on the strength and lifetime of the CNC machine tool is discussed by using fatigue analysis. Consequently, this research can be used for efficient simulation of structural dynamics, lifetime assessment and interactions of the real CNC machine with the machine tool structure in a virtual environment.

The fiber orientation is considered one of the important parameters that have an effect on the characteristics of composites. This paper aims to investigate the effect of fiber orientation on the abrasive wear of the glass-epoxy (G-E) composites with different silicon carbide (SiC) filler weights (Wt.%).

The wear rate of glass fiber reinforced with angle-ply 0º, ±45º and 90º is discussed. The G-E composites with different weights of SiC filler at angle ±45º are considered. Hand lay-up technique was adopted for specimen preparation. The influence of effective parameters such as filler Wt. %, normal load, abrasive size and abrading distance on the wear rate was presented and discussed.

Experimental tests including pin on disk, micro-hardness and scanning electron microscope were carried out to investigate the composite characteristics.

The experimental results showed that the resistance wear was superior in case of ±45º fiber orientations. A validation of the experimental results using Taguchi approach to verify the optimal wear rate parameters was presented.

This paper aims to investigate the effects of plasma nitriding and Ti-C:H coating deposition on AISI 316L and to find the best tribological performance of various specimens.

An experimental investigation is performed into the effects of plasma nitriding and Ti-C:H sputtering on the tribological properties of AISI 316L biomedical stainless steel. Five samples are prepared, namely, original AISI 316L stainless steel (code: 316L), nitrided 316L (code: N316), 316L and N316 sputtered with Ti-C:H (codes: D316 and DN316, respectively) and polished N316 sputtered with Ti-C:H (DN316s). The microstructure, mechanical properties and coating adhesion strength of the various samples are investigated and compared. The tribological properties of the samples are then evaluated by means of reciprocating wear tests performed in 8.9 Wt.% NaCl solution against three different counterbodies, namely, a 316L ball, Ti₆Al₄V ball and Si₃N₄ ball.

It is shown that plasma nitriding followed by Ti-C:H deposition (DN316s) improves the tribological properties of AISI 316L; the sample provides the best tribological performance of the various specimens and has a wear rate approximately 156 times lower than that of the original 316L substrate.

The results suggest that nitriding followed by polishing and Ti-C:H sputtering provides an effective means of improving the service life of AISI 316L biomedical implants.