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PTFE coatings were deposited on YT15 carbide substrates using spray technology. A series of examinations were conducted, including the use of surface and cross-section micrographs to analyze the structural integrity of the coatings. The surface roughness, the adhesion force between the PTFE coatings and the carbide substrate, and the micro-hardness of the coated carbide were also evaluated. Additionally, the friction and wear behaviors were assessed through dry sliding friction tests against WC/Co balls. The test results indicated that while the PTFE-coated carbide exhibited a rougher surface and reduced micro-hardness, it also demonstrated a significant reduction in surface friction and adhesive wear. These findings suggest that the PTFE coatings enhance the overall wear resistance of the carbides. The lower surface hardness and shear strength of the coatings influenced the friction performance, leading to specific wear failure mechanisms, such as abrasion wear, coating delamination, and flaking. Overall, the deposition of PTFE coatings on carbide substrates presents a promising strategy to enhance their friction and wear performance. This approach not only improves the durability of carbide materials but also offers potential applications in industries where reduced friction and wear are critical for performance. [ABSTRACT FROM AUTHOR]

To improve the surface friction characteristics of cemented carbide, a Cr coating was deposited on cemented carbide substrate with the multiple arc plating technique. The surface and cross-section micrographs, adhesion force and micro-hardness of the Cr-coated cemented carbide were tested. The anti-friction and anti-wear behaviors of cemented carbide with and without Cr coating were investigated via the sliding friction test against a WC/Co ball. The tribological properties of cemented carbide were examined using a scanning electron microscope and energy dispersive X-ray analysis. The test results showed that Cr-coated cemented carbide possessed good adhesion properties and lower hardness. The average coefficient of friction for Cr-coated cemented carbide was reduced by 10–20% compared with that of an uncoated one. The primary wear modes of the Cr-coated sample were delamination of coating, flaking and abrasion wear. It can be found that the preparation of a Cr coating is an effective way to enhance the friction and wear performance of traditional cemented carbide. [ABSTRACT FROM AUTHOR]

For the bearing rock in geotechnical engineering, it is frequently affected by external loads. This paper adopted different upper limits of stress to carry out cyclic loading-unloading on the sandstone specimens to make them in different damage degrees and analyzed the mechanical mechanism of the damaged sandstone under different stresses. Then, the strength change and energy evolution of sandstone with different damage degrees were analyzed, and the damage of the loaded sandstone was quantitatively characterized. The experimental results showed that the strength and plastic deformation of sandstone after cyclic loading-unloading with different upper-stress limits gradually decreased with the increase of the upper-stress limit. In the loading-unloading stages of cyclic loading-unloading, the elastic modulus increased with the increase of the upper-stress limit. In general, as the number of cycles increased, the total strain energy density and elastic deformation energy density gradually increased, and as the upper-stress limit increased, both of them also increased. The damage factor of sandstone after cyclic loading-unloading, which was characterized by dissipated energy, increased in an S-shape with the increase of the upper-stress limit, and the growth rate first increased and then decreased. [ABSTRACT FROM AUTHOR]

To expand the industrial application of cemented carbide, micro-EDM was utilized to machine microhole-textures on the carbide surface; graphite powder was burnished into the textured microholes. The tribological properties of the microhole-textured tool combined with graphite were investigated and compared with the conventional one by carrying out reciprocating sliding friction tests and dry machining tests. Results exhibited that the microhole-textured tool combined with graphite possessed a much lower friction coefficient than that of the conventional one in sliding tests. The cutting forces, average friction coefficient at the tool–chip interface, and rake face wear of the textured tool were reduced, and the workpiece surface quality was also slightly improved. The worn regions of carbide specimen were examined and studied, and the possible effect mechanisms for the enhancement of friction and wear properties mainly consisted of the formation of uneven graphite film by friction extrusion, reduction of actual contact length, entrapment of wear debris and supply of graphite lubricant. [ABSTRACT FROM AUTHOR]

To improve the tribological properties of pure MoS2 coating, the MoS2–Zr composite lubricating coatings were prepared on the WC/TiC/Co carbide surface utilizing radio frequency magnetron sputtering method combining with multiple arc ion plating technology. The effects of different Zr target currents on the surface morphologies, roughness, Zr content, adhesive force, thickness, microhardness and tribological behaviors of the composite coatings were systematically investigated. Results showed that the properties of MoS2 coating can be remarkably enhanced through co-deposition of a certain amount of Zr. As the Zr target current increased, the Zr content, surface roughness, thickness, and micro-hardness gradually increased, while the adhesive force of coatings increased first and then decreased. The friction behaviors and wear modes of the composite coatings both varied obviously with the increase of Zr current. The mechanism was mainly attributed to the different components and mechanical properties of the coatings caused by various Zr current. [ABSTRACT FROM AUTHOR]

To enhance the friction and wear performance of cemented carbide, textured microholes were machined on micro Electron Discharge Machining (EDM) on the tool rake face, and Calcium Fluoride (CaF2) powders were burnished into the microholes. The friction and wear characteristics of the microhole-textured tool filled with CaF2 were investigated using sliding friction tests and dry cutting tests. Results exhibited that the working temperature could affect the tribological performance of the microhole-textured tool filled with CaF2 due to the temperature-sensitive nature of CaF2. There is no obvious lubrication effect for the textured tool filled with CaF2 at room temperature, while it was shown to be more effective in improving tribological property at a cutting speed of higher than 100 m/min with a corresponding to cutting temperature of 450 °C. The possible mechanisms for the microhole-textured tool filled with CaF2 were discussed and established. [ABSTRACT FROM AUTHOR]

In order to enhance the tribological performance of YT14 carbide, pure Zr coating was deposited on the substrate surface using a multi-arc ion plating method. The surface topography, adhesion strength, thickness, and micro-hardness of the Zr coating were tested. Dry sliding friction experiments against a 40Cr hardened steel ring were conducted with Zr-coated carbides and traditional ones. The average coefficients of friction were measured and compared. The wear characteristics of the samples were examined by scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX). The test results indicated that the Zr coating deposited on the carbide surface exhibited excellent adhesive strength and lower hardness. The average friction coefficient of Zr coated carbide decreased by 20%–30% in comparison with that of the uncoated one. The Zr coated carbide could reduce the adhesive wear compared with the uncoated one, and the main tribological degradation mechanisms of the coating were abrasive wear, coating flaking and delamination. [ABSTRACT FROM AUTHOR]