Wear Properties Of Composite Coatings Research Articles

Microstructure and Properties of FeAlC-x(WC-Co) Composite Coating Prepared through Plasma Transfer Arc Cladding

Tungsten carbide (WC) is widely used in wear-resistant parts due to its excellent wear resistance. Iron-based alloys are used in the repair and remanufacturing of engine components due to their good compatibility with iron-based workpieces. In order to enhance the wear resistance of engine components in service under abrasive conditions, composite coatings have been prepared for cast iron engine components by adding WC-Co to iron-based powders. This study investigates the microstructure and wear properties of composite coatings of iron-based alloys reinforced with different contents of WC particles. The composite coatings mainly contained γ-Fe, α-Fe, WC and Fe3W3C. With the addition of the WC-Co strengthening phase, the average hardness of the FeAlC-x(WC-Co) composite coatings increases from 524 HV0.2 to 814 HV0.2. Wear test results showed that when the WC addition was 20%, it had the lowest frictional coefficient of 0.5 and the lowest wear mass loss of 1.3 mg. Compared to the original Fe-based alloy coatings, the WC particle-reinforced FeAlC composite coatings display improved wear resistance on a reduced friction basis, mainly benefiting from the high wear resistance of the graphite solid lubrication phase and carbides in the cladding.

Comparative Investigation on Wear Properties of Composite Coatings with Varying CeO2 Contents

Several innovative mixed powders of Ti6Al4V and NiCr-Cr3C2 with different CeO2 contents (0, 1, 2, 3, and 4 wt.%) were designed, and Ti2C-reinforced CrTi4-based composite coatings were prepared on the Ti6Al4V surface via laser cladding technology. The effects of CeO2 amount on the forming quality, microstructure, hardness, and wear resistance of the composite coatings were studied. The results showed that the CeO2 amount had a significant influence on the forming quality of the composite coatings. The cracks were eliminated completely when the CeO2 content was 2 wt.%; furthermore, the lowest porosity was obtained with the addition of 3 wt.% CeO2. The primary phase constituents of the coatings were non-stoichiometric Ti2C and a β-type solid solution (CrTi4) as the reinforcement and matrix, respectively. CeO2 and a low quantity of Ce2O3 were re-precipitated at the Ti2C/CrTi4 interface and CrTi4 grain boundary in the coatings with CeO2 addition. In addition, the average hardness of the composite coatings was 1.28–1.34 times higher than that of the Ti6Al4V substrate. The wear resistance of the composite coatings was significantly higher than that of the substrate. However, both the composite coatings and the Ti6Al4V substrate exhibited a mixed-wear mode, i.e., abrasive and adhesive wear.

Correlation between pulsed laser parameters and MC carbide morphology in H13 tool steel/TiC composite coating

In this study, composite coatings were fabricated by preplacing a TiC layer on H13 tool steel and surface melting with a pulsed Nd: YAG laser. Since the morphology of hard phase particles is one of the determinants of the wear properties of composite coatings, the role of process variables on the shape and size of carbide precipitates was investigated. The transverse cross-section of the laser-scanned samples was studied by an optical microscope to evaluate the geometrical changes of alloyed areas. Scanning electron microscopy and X-ray energy dispersive spectroscopy were used to probe the microstructure and chemical composition of the coating layers. X-ray diffraction was used to identify the phases. The results showed that by the partial or total dissolution of TiC particles in the melt pool, TiC-type MC carbides precipitated as the primary phase. Alterations in pulse laser variables changed the geometry of the alloyed region and hence the concentration of dissolved Ti and C elements in the composite coating. Investigation of the effect of the laser variables in the form of “effective peak power density” (EPPD) revealed that increasing the EPPD led to an increase in the Fe/Ti weight ratio in the composite. As the Fe/Ti weight ratio increased, the shape of the MC precipitates changed gradually, from fully developed dendrites to petal, and polyhedral morphology.

Effect of submicron Sn on wear resistance and scale resistance of Ni–P–Sn composite coating

In this experiment, the microstructure and mechanical properties of Ni–P–Sn composite coatings with different Sn contents were observed by scanning electron microscope, optical contact angle measuring instrument, Vickers hardness tester and other experimental equipment. The effects of different Sn contents on wear resistance and scale resistance of Ni–P–Sn composite coatings were studied. The friction and wear properties of composite coatings with different Sn contents are tested and analyzed on friction and wear instruments, and the influence of Sn content on the scale resistance of composite coatings is analyzed through surface free energy and scale adhesion experiments. The results show that by measuring the hardness values of Ni–P– submicron Sn(2 g l−1) coating, Ni–P coating and Q235, it is found that the hardness value of Ni–P–Sn composite coating is the highest, 434.9 HV. At the same time, it is concluded that adding Sn to Ni–P composite coating is helpful to reduce the friction coefficient of the coating. The friction coefficient of Ni–P–Sn composite coating (6 g l−1) is 16.04% lower than that of the coating without Sn. When Sn content is 6 g l−1, the wear resistance is the best. When Sn content is 2 g l−1, the contact angle is 120.2° at the maximum. The minimum surface free energy is 15 MJ m−2. The dirt weight gain is the minimum value of 85 g m−2. At this time, the anti-fouling performance is the best.

Characteristics of Laser Cladded Nickel-Based Chromic Carbide Composite Coatings

To improve the surface hardness and wear resistance of metal parts. Ni-based chromic carbidecomposite coating was prepared on the carbon steel (0.45 mass% C) substrates by laser cladding. Microstructure and wear properties of composite coatings were investigated by SEM, EDS, XRD, Vickers micro-hardness tester and wear machine. The results show that good metallurgical bonding between the Ni-based chromic carbidecomposite coating and carbon steel substrate. Micro-hardness of Ni-based Cr3C2 composite coating along the layer depth presents an evident stepladder distribution. The average micro-hardness of the laser clad coating is about 950 HV. The result of wear experiment shows that Ni-based Cr3C2 composite coating processes good wear resistance.

Effect of sol aging time on the wear properties of TiO2–SiO2 composite films prepared by a sol–gel method

TiO2–SiO2 composite films were deposited on commercially pure titanium (Cp-Ti) substrate with composite sols of different aging times (unaged, 1, 3, 10 weeks) by a sol–gel method. The effects of aging time on the structural, mechanical and wear properties of composite coatings were investigated using pin-on-disk tribotester. The structure of composite coatings was analyzed with XRD and SEM. The wear volume of TiO2–SiO2 composite films were investigated with 3D profilometer. Tribological properties of the composite films were significantly influenced by aging time. Composite coatings prepared from unaged sol showed the best wear resistance. This may be attributed to their high surface hardness, low surface roughness and self-lubricant phase structure. It was observed that increasing aging time led to increase the grain size. It was obtained that the wear volume values increased with increasing aging time.

Microstructure and tribological properties of laser clad Ni-Ag/Tic composite coating

Ni-Ag/TiC composite coating was prepared on the 45 steel substrates by means of laser cladding. Microstructure and wear properties of composite coatings were analyzed using optical microscopy, field emission scanning electron microscopy and wear machine. The experimental results show that defects, such as cracks and pores, do not occur in the laser-cladded Ni-Ag/TiC composite coating and 45 steel substrate, and they present good metallurgical bonding between them. Compared with Ni/TiC composite coating, microhardness values of the two coatings do not present evident differences. The wear experiment result shows that Ni-Ag/TiC composite coated with Ag possesses low friction coefficient and good wear resistance compared with Ni/TiC composite coating.

Corrosion and Wear Properties of Composite Coatings Reinforced with Particles Produced by PTA on Steel Substrate in Different Atmospheres

Titanium diboride (TiB2) and titanium carbonitride (Ti(C,N)) coatings are widely used as reinforcing materials in applications demanding high corrosion and wear resistance. In this paper, plain carbon steel has been surface alloyed with TiB2 by plasma transferred arc (PTA) technique using two different gas atmospheres. The first metal matrix composite (MMC) is produced with TiB2 particles and argon as shielding and plasma gas. In addition, a mixture of Ar and 5% N2 was used as shielding and plasma gas for producing of second MMC coating. The microstructure of both alloyed layers consists of primary titanium boride particles surrounded by a eutectic matrix, containing ferrite, eutectic boride, and titanium carbonitrides. The presence of these carbonitrides is more intense in the case of the N-enriched alloyed layer, as it was also proved via X-ray Diffraction. The alloyed layers are susceptible to pitting corrosion in 3.5% NaCl or 1 N H2SO4. The alloyed layer produced with nitrogen mixture gas is slightly more noble than the one produced with pure Ar. The metallic-ferritic matrix corrodes in 6% FeCl3∗6H2O leaving TiB2 particles protruding from the matrix. The wear performance of both TiB2 MMC depends on the counterbody (tool steel or alumina ball).

Microstructures and wear properties of composite coatings produced by laser alloying of Ti–6Al–4V with graphite and silicon mixed powders

Composite coatings were fabricated by laser alloying of titanium alloy Ti–6Al–4V with graphite and silicon mixed powders. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis indicate that the coatings mainly consist of preeutectic TiC and eutectic Ti5Si3+β(Ti). The test results show that the composite coatings, thickness of about 0.6 mm, surface microhardness of about 1500 HV0.1, have a lower friction coefficient and a much higher wear resistance than the as-received sample.