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Auezhan Amanov – One of the best experts on this subject based on the ideXlab platform.
wear resistance and Adhesive Failure of thermal spray ceramic coatings deposited onto graphite in response to ultrasonic nanocrystal surface modification techniqueApplied Surface Science, 2017Co-Authors: Auezhan AmanovAbstract:
Abstract In this study, thermal spray ceramic (TSC) coatings sprayed onto a graphite were subjected to ultrasonic nanocrystal surface modification (UNSM) technique. The surface roughness of the as-received Cr3C2, ZrO2 and Al2O3 coatings was reduced by about 28, 24 and 9% after UNSM treatment, which can be explained that the high peaks were removed during UNSM treatment, where a flat surface area is enlarged due to the partially elimination of single- and interconnected micro-pores. In addition, the number of cracks is also reduced by filling up the cracks by a smashed coating powder due to the continuous high-frequency strikes of a tip to the surface of the coating resulting in increase in surface hardness of the as-received Cr3C2, ZrO2 and Al2O3 coatings by about 14, 10 and 6% after UNSM treatment, respectively. The wear resistance and Adhesive Failure of the coatings were improved after UNSM treatment as well representing a remarkable influence on the friction and wear performance, and the critical load of the coatings. Hence, it is expected that a hybrid use of TSC coatings with UNSM technique is beneficial to improving the surface and adhesion behavior of the coatings to be applied to a graphite mold to produce a glass.
Wear and Adhesive Failure of Al_2O_3 Powder Coating Sprayed onto AISI H13 Tool Steel SubstrateJOM, 2016Co-Authors: Auezhan Amanov, Young-sik PyunAbstract:
In this study, an alumina (Al_2O_3) ceramic powder was sprayed onto an AISI H13 hot-work tool steel substrate that was subjected to sanding and ultrasonic nanocrystalline surface modification (UNSM) treatment processes. The significance of the UNSM technique on the Adhesive Failure of the Al_2O_3 coating and on the hardness of the substrate was investigated. The Adhesive Failure of the coating sprayed onto sanded and UNSM-treated substrates was investigated by a micro-scratch tester at an incremental load. It was found, based on the obtained results, that the coating sprayed onto the UNSM-treated substrate exhibited a better resistance to Adhesive Failure in comparison with that of the coating sprayed onto the sanded substrate. Dry friction and wear property of the coatings sprayed onto the sanded and UNSM-treated substrates were assessed by means of a ball-on-disk tribometer against an AISI 52100 steel ball. It was demonstrated that the UNSM technique controllably improved the Adhesive Failure of the Al_2O_3 coating, where the critical load was improved by about 31%. Thus, it is expected that the application of the UNSM technique to an AISI H13 tool steel substrate prior to coating may delay the Adhesive Failure and improve the sticking between the coating and the substrate thanks to the modified and hardened surface.
R M Souza – One of the best experts on this subject based on the ideXlab platform.
numerical evaluation of cohesive and Adhesive Failure modes during the indentation of coated systems with compliant substratesSurface & Coatings Technology, 2014Co-Authors: N K Fukumasu, R M SouzaAbstract:
Abstract The indentation of coated systems allows the analysis of the mechanical properties of each individual constituent, or of the entire system, including material constitutive behavior and Failure properties. Due to the progressive loading and unloading of the indentation cycle, both cohesive and Adhesive Failures can occur in the coating and at the coating/substrate interface, respectively. In this work, the Finite Element Method (FEM) was applied to develop a numerical model based on a spherical rigid indenter in contact with a coated compliant substrate. The coating behavior was defined based on the properties of brittle pure elastic materials, while the substrate was assumed elastic-perfectly plastic. Both cohesive and Adhesive Failure models were included in the analyses, allowing the evaluation of Failure in the coating and/or at the coating/substrate interface. The eXtended Finite Element Method (XFEM) was applied to reproduce the cohesive cracks through the coating thickness, while the Cohesive Zone Model (CZM) was used to evaluate the coating/substrate interfacial crack. System Failure was analyzed considering a range of coating parameters (elastic modulus, fracture toughness, energy release rate for cohesive propagation, thickness and residual stresses), coating/substrate interface properties (interface toughness and Adhesive crack energy release rate) and the radius of the spherical indenter. The range of input values resulted in simulations with cohesive and/or Adhesive Failures and allowed determination of a parameter that presented good correlation with the occurrence of crack propagation and Failure. Cohesive Failures in the coating also produced signatures on the load–displacement (P–h) indentation curves, which allowed the evaluation of coating fracture toughness with good agreement with the input toughness values in cases where the coating was thin.
Ralph Spolenak – One of the best experts on this subject based on the ideXlab platform.
cohesive and Adhesive Failure of hard and brittle films on ductile metallic substrates a film thickness size effect analysis of the model system hydrogenated diamond like carbon a c h on ti substratesActa Materialia, 2015Co-Authors: Daniel Bernoulli, K Hafliger, Kerstin Thorwarth, G Thorwarth, R Hauert, Ralph SpolenakAbstract:
Abstract Using the model system hydrogenated diamond-like carbon (a-C:H) on titanium (Ti) substrates the effect of a changing film thickness on the cohesive and Adhesive Failure of hard and brittle films on ductile metallic substrates is analyzed by uniaxial loading. A film thickness size effect has been observed for the fracture strength and the onset strain of delamination. For a a-C:H film thickness 1 μm, whereas for film thicknesses of 200 and 500 nm the effect of the strain is only secondary. Upon uniaxial loading the Ti substrate exhibits an anisotropic deformation which affects the cohesive and Adhesive Failure of thin a-C:H films. The energy release rates for cohesive and Adhesive Failure and the fracture toughness of a-C:H are all independent of film thickness. The corresponding values have been determined to be 63.5 ± 2.6 J m −2 , 579 ± 20 J m −2 and 3.2 ± 0.1 MPa m 1/2 , respectively. Finally, a schematic is presented to determine qualitatively the adhesion of ductile and moderately brittle films on any kind of substrate.