Wear Resistance Of Ceramic Coatings Research Articles

Reduction of Shear Stresses in Friction Units with an Electrical Insulation Coating of the ITER Blanket Modules

During operation of the International Thermonuclear Experimental Reactor (ITER), its removable blanket modules undergo significant shock loads in the process of plasma disruption, which lead to the displacement of parts with a gas-thermal insulating coating on the mount points of the protective panels of the vacuum chamber. A high friction coefficient $$f~$$ ≥ 0.28 at maximum shear resistance provokes peeling, fracturing, and chipping of insulating coatings. Methods of reducing the friction coefficient of supporting surfaces coated with an electrical insulation coating (Al2O3, MgAl2O4) and mount points of the ITER blanket modules experiencing significant shear stresses are considered. The tribotechnical tests of electrical insulating coatings paired with the proposed modified zirconium alloy plates with an antifriction layer in the range of sliding speeds $${v}$$ = 10–5−10–2 m/s, loads $$N$$ = 100−600 N according to the pin-on-disk scheme at temperatures $$T$$ = 20°C, T = 250°C showed a change in the friction coefficient in the range $$f$$ = 0.08−0.23 and high wear resistance of ceramic coatings. The use of innovative intermediate plates with a modified layer (ZrO2−C) in blanket modules could be an alternative to low pressure plasma spraying of an antifriction MoS2 finish layer on electrical insulation coatings.

Effects of current frequency on the MAO coatings on AA7050

ABSTRACT In order to solve the corrosion and wear of 7050 aluminium alloy (AA7050) caused by the marine environment and prepare excellent coating structure to prolong its service life, the micro-arc oxidation (MAO) ceramic coatings were prepared at the current frequency of 50, 250, 500, 750, 1000 Hz in the silicate electrolyte, respectively. To analyse the surface morphology, phase composition, corrosion resistance and wear resistance of ceramic coatings, the scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical workstation, friction-abrasion tester were used. The results showed that when the current frequency was too low, the mono-pulse energy would be too high and the surface of MAO ceramic coating would be rough, which affected the compactness of the coating. Nevertheless, when the current frequency was too high, it will be unfavourable to the growth of MAO ceramic coating, and the corrosion resistance and wear resistance of the as-prepared coatings were poor.

Plasma transferred arc surface modification of atmospheric plasma sprayed ceramic coatings

In this study, a 90MnCrV8 steel surface was coated with aluminum oxide and chromium oxide powders through the Atmospheric plasma spray (APS) and Plasma transferred arc (PTA) methods. The effects of PTA surface melting on the microstructure, hardness, and wear behavior were investigated. The microstructures of plasma-sprayed and modified layers were characterized by Optical microscopy (OM), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). The dry-sliding wear properties of the samples were determined through the ball-on-disk wear test method. Voids, cracks, and nonhomogeneous regions were observed in the microstructure of the APS ceramic-coated surface. These microstructure defects were eliminated by the PTA welding process. The microhardness of the samples was increased. Significant reductions in wear rate were observed after the PTA surface modification. The wear resistance of ceramic coatings increased 7 to 12 times compared to that of the substrate material.

Effects of Current Frequency on the Microstructure and Wear Resistance of Ceramic Coatings Embedded with SiC Nano-particles Produced by Micro-arc Oxidation on AZ91D Magnesium Alloy

To improve the surface wear resistance of the ceramic coating fabricated by micro-arc oxidation (MAO) on AZ91D magnesium alloy, ceramic coatings embedded with SiC nano-particles at different current frequency (500 Hz, 700 Hz, and 900 Hz) were produced during the MAO process. The morphology and phase composition of the coatings were investigated by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The surface roughness of the coatings was characterized by confocal laser scanning microscopy (CLSM). Simultaneously, the tribological properties of the composite coatings were evaluated by using a universal materials tester (UMT). The results shows that the wear resistance of the ceramic coatings with SiC nano-particles was improved significantly compared to the ceramic coatings without SiC nano-particles. Furthermore, the composite coating formed at current frequency 900 Hz showed the better wear resistance than the others.

A Multi RIG Screening Test for Thin Ceramic Coatings in Bio - Tribological Applications

A method is presented for the comparative testing of wear resistance of ceramic coatings made from materials potentially feasible in tribo - medical applications, mainly orthopaedic implants made from ceramics coated metals for low cost, long life and low wear particle emission into the body. The method was devised as the main tool for use in research and is comprised of flat on flat and ball on flat surface (sliding) tests. Seven ceramic coatings were chosen as potentially feasible for the application area known to perform well in low viscosity fluid lubrication condition. The materials used in coatings were diamond like carbon (DLC), diamond like carbon with tungsten additive (DLC-W), titanium nitride (TiN), titanium carbide (TiC), silicon carbide (SiC), chromium nitride (CrN), carbon nitride (CNx). The coatings tested were deposited in vacuum to a stainless steel substrate with the use of several methods, each suited to the coating material; The methods were the following: cathode arc evaporation (ARC), magnetron sputtering (MAG), plasma assisted chemical vapour deposition (PACVD), impulse reactive magnetron sputtering (IRMS) and a combined method ARC-MAG-RF-PACVD (radio frequency assisted - RF); A multiple role PT-3 tribometer was used for flat on flat surface tests (ring shaped surface) and a reciprocating linear motion TPZ-1 tribometer for ball on flat surface tests and a CSEM REVETEST® Scratch Tester to perform standard scratch test in air on coatings. A set of results was obtained illustrating the limiting load for each coating (the load inflicting rapid destruction of the coating) and the endurance under light loading conditions. As lubricating agents distilled water and saline water solution were used. Test results examples are presented and discussed as an illustration of the method's usability for the target application area.

Laser remelting of plasma sprayed Al 2O 3 ceramic coatings and subsequent wear resistance

This paper deals with the laser melting of Al 2O 3 and Al 2O 3+13wt.%TiO 2 ceramic coatings deposited by atmospheric plasma spraying. After laser melting, metastable phase γ-Al 2O 3 transforms into stable phase α-Al 2O 3 in Al 2O 3 coatings, whereas in Al 2O 3+13wt.%TiO 2 coatings besides this phase transformation, TiO 2 may react with Al 2O 3 and transform into TiAl 2O 5. The melting layer becomes much denser and, hence, its hardness has been greatly developed despite the existence of some cracks. Furthermore, the increase in hardness of the melting layers is almost independent of coating type and generally increases with the laser energy density. However, the coating type has a strong influence on the thickness of the laser melting layers. As to the coatings with the same coating type, the depth of laser melting roughly increases with the laser energy density. Finally, it has been found that the introduction of TiO 2 can improve the wear resistance of ceramic coatings, particularly, of the melting layers, although TiO 2 reduces the hardness of these ceramic coatings.

The abrasive wear resistance of ceramic coatings on metals

The abrasive wear resistance of ceramic coatings on metals