Effect of the surface microstructure of SiC inner coating on the bonding strength and ablation resistance of ZrB2-SiC coating for C/C composites

The direct injection molding process of PPS-aluminum alloy composite parts under vacuum condition was conducted and the processing parameters were optimized through the numerical simulation and orthogonal test design. The effect of surface microstructure of the aluminum alloy splines and injection molding processing parameters on the bonding strength of the composite parts were discussed. The results show that the bonding strength of the composite parts increases with not only the increase in the diameter and quantity of the microscopic pores and also the surface roughness of the aluminum alloy splines. The bonding strength can also been improved under a higher vacuum. The bonding strength is highly correlated to the micromechanical interlocking structure formed by the PPS embedding into the rough surface of the aluminum alloy splines.

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Influence of Bond Coat on Thermal Shock Resistance and Thermal Ablation Resistance for Polymer Matrix Composites

Frontiers in Materials ◽

10.3389/fmats.2021.672617 ◽

2021 ◽

Vol 8 ◽

Author(s):

Jiahui Zhou ◽

Jianing Jiang ◽

Longhui Deng ◽

Jingqi Huang ◽

Jieyan Yuan ◽

...

Keyword(s):

Residual Stress ◽

Thermal Shock ◽

Bonding Strength ◽

Thermal Ablation ◽

Thermal Shock Resistance ◽

Polymer Matrix Composites ◽

Coating System ◽

Matrix Composites ◽

Ablation Resistance ◽

Shock Resistance

Polymer matrix composites (PMCs) have been widely used in aero industry because of its low density and high strength-to-weight ratio. However, the application of PMCs is still limited by poor abrasion resistance, weak oxidation resistance and low operation temperature. In this study, Cu (Al)/NiCrAlY/YSZ triple layer coating system was deposited on glass fiber reinforced polyimide matrix composites (FPM) by means of High Velocity Oxygen Fuel (HVOF) for metallic coatings and Atmospheric Plasma Spraying (APS) for YSZ coating. The influences of different bond coats and different thickness of the top coat on the thermal shock resistance and thermal ablation resistance of the coating system was investigated. Compared with Al particle, Cu particle has a high density and correspondingly a high kinetic energy during spraying by HVOF, resulting in a high bonding strength between the Cu coating and FPM substrate. In the thermal shock test, the coating Cu/NiCrAlY/YSZ has a much longer lifetime than the coating Al/NiCrAlY/YSZ. After high-speed impact on the substrate, there is a great compressive stress at the interface, which makes a plastic deformation to the substrate, and the particles are closely embedded into the substrate to form a strong mechanical interlock. The coating system consisting of 50 μm Cu, 50 μm NiCrAlY, and 200 μm 8YSZ exhibited the best thermal shock resistance, thermal ablation resistance and bonding strength. The increase of the top coat thickness will lead to the increase of residual stress and the decrease of bonding strength. The failure mechanism of the coating is mainly attributed to the residual stress in the deposition process and the thermal stress caused by thermal expansion mismatch.

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SiCnw/PyC core-shell networks to improve the bonding strength and oxyacetylene ablation resistance of ZrB2–ZrC coating for C/C–ZrB2–ZrC–SiC composites

Carbon ◽

10.1016/j.carbon.2017.09.019 ◽

2017 ◽

Vol 124 ◽

pp. 675-684 ◽

Cited By ~ 23

Author(s):

Lei Zhuang ◽

Qian-Gang Fu ◽

He-Jun Li

Keyword(s):

Bonding Strength ◽

Core Shell ◽

Ablation Resistance ◽

Sic Composites ◽

Zrc Coating

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Preparation of Backthinned Ceramic Specimens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117881 ◽

1985 ◽

Vol 43 ◽

pp. 182-183

Author(s):

A. T. Fisher ◽

P. Angelini

Keyword(s):

Electron Microscopy ◽

Analytical Electron Microscopy ◽

Vacuum System ◽

Back Surface ◽

Surface Microstructure ◽

Ion Milling ◽

Near Surface ◽

Depth Profiles ◽

Analytical Electron ◽

Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

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