Experimental study on heat insulation performance of functionally graded metal/ceramic coatings and their fracture behavior at high surface temperatures

2005 ◽  
Vol 194 (2-3) ◽  
pp. 203-214 ◽  
Author(s):  
Hua-Ping Xiong ◽  
Akira Kawasaki ◽  
Yan-Sheng Kang ◽  
Ryuzo Watanabe
2013 ◽  
Vol 750-752 ◽  
pp. 2200-2205 ◽  
Author(s):  
Cheng Fan

In this presented work, a coupled thermo-mechanical model is employed to analyze the thermo-mechanical behavior of ceramic functionally graded materials (FGMs) and the crack formation and propagation process of ceramic coating was simulated step in step and step by step using the RFPA (Realistic Failure Process Analysis) 2D-Thermo code. The thermal shock fracture behavior is discussed based on the basis of the simulated crack morphology and elucidated the mechanism of crack deformation and crack propagation. The state change from compression to tension whose magnitude is large enough to exceed the tension strength of ceramic causes the vertical crack. The numerical results agreed well with the experimental results in the previous literature.


Silicon ◽  
2018 ◽  
Vol 10 (5) ◽  
pp. 2341-2351
Author(s):  
M. Esfandyari ◽  
H. Salehi ◽  
D. Jafari ◽  
M. Koolivand-salooki ◽  
J. R. Esfandyari

2001 ◽  
Author(s):  
Hugh A. Bruck ◽  
Harishbabu Surendranath

Abstract There is a great deal interest in minimizing thermal and residual stresses at the interfaces of metals and ceramics. These stresses develop because of the large mismatch in thermally induced strains that exists between these two materials. The differences are significant enough to cause premature component failure in a variety of applications, including thermal barrier coatings (TBCs) for turbine blades and ceramic coatings for cutting tools. One approach to minimizing these stresses involves functionally grading the material distribution at the metal-ceramic interface. A significant amount of effort has been focused on the development of functionally graded nickel-alumina composites as a model system to determine the architectural features of the material gradient that will minimize these stresses. This effort has led to the development of an experimentally verified modeling approach based on thermomechanical, elastoplastic finite element analysis that can be used to predict the stress distributions in functionally graded metal-ceramic composite materials. This approach has been coupled with a mathematical optimization technique, known as a Genetic Algorithm (GA), to determine the optimal architecture for minimizing thermal and residual stresses at metal-ceramic interfaces.


2003 ◽  
Vol 778 ◽  
Author(s):  
Shane A. Catledge ◽  
Yogesh K. Vohra ◽  
Shanna Woodard ◽  
Ramakrishna Venugopalan

AbstractA functionally graded nanocrystalline metalloceramic coating on cobalt-chrome alloy was investigated using thin film x-ray diffraction (XRD), cross-sectional transmission electron microscopy (TEM), nanoindentation, and scratch adhesion testing. The gradual transition in bonding from metallic (Cr/CrTi) near the interface to predominantly covalent (CrTiN) near the surface provides a combination of high toughness and high surface hardness. XRD analysis of the (CrTiN) coating suggests a cubic sodium chloride type phase structure with lattice parameter a = 4.2169±0.0035 Å. The surface layer structure is described as a tertiary Ti-N-Cr disordered solid solution that is predominantly cubic TiN, but with some Cr atoms substituted for Ti. TEM shows a transition from equiaxed 20-40 nm-sized grains at the surface to larger, elongated columnar grains below the surface. Nanoindentation measurements of the coating result in a hardness of 27 GPa and Young's modulus of 320 GPa. In addition, the high plasticity of 55% observed for this coating represents an increase in toughness over other ceramic coatings having similar hardness. The unique, functionally graded, smooth nanocrystalline metalloceramic coating structure provides an opportunity to reduce wear and increase longevity of total hip joint replacements.


2020 ◽  
pp. 2-11
Author(s):  
N. V. TITOV ◽  
◽  
A. V. KOLOMEYCHENKO ◽  
V. L. BASINYUK ◽  
I. N. KRAVCHENKO ◽  
...  

2021 ◽  
Vol 11 (15) ◽  
pp. 7043
Author(s):  
Tun-Ping Teng ◽  
Shang-Pang Yu ◽  
Yeou-Feng Lue ◽  
Qi-Lin Xie ◽  
Hsiang-Kai Hsieh ◽  
...  

This study selects titanium dioxide (TiO2) and multi-walled carbon nanotubes (MWCNTs) as far-infrared materials (FIRMs), and further adds water-based acrylic coatings to prepare far-infrared coatings (FIRCs). FIRCs are uniformly coated on #304 stainless steel sheets to make the test samples, which are then installed between the shell and insulation material of the hot water heater to measure the influences of various FIRCs on the performance of the hot water heater. The research results show no significant difference in the heating rate or heat insulation performance of the hot water heater with or without FIRCs coating. However, the uniformity of the water temperatures of the test samples is significantly improved with FIRCs. Considering that the uniformity of water temperature will inhibit the heating rate and heat insulation performance of the hot water heater, TiO2-FIRC should provide better performance improvement when applied to the hot water heater in this study. The application of TiO2-FIRC to large-scale hot water heaters with a high aspect ratio will effectively improve the quality of hot water supply in the future.


Author(s):  
Lukas Seeholzer ◽  
Stefan Süssmaier ◽  
Fabian Kneubühler ◽  
Konrad Wegener

AbstractEspecially for slicing hard and brittle materials, wire sawing with electroplated diamond wires is widely used since it combines a high surface quality with a minimum kerf loss. Furthermore, it allows a high productivity by machining multiple workpieces simultaneously. During the machining operation, the wire/workpiece interaction and thus the material removal conditions with the resulting workpiece quality are determined by the material properties and the process and tool parameters. However, applied to machining of carbon fibre reinforced polymers (CFRP), the process complexity potentially increases due to the anisotropic material properties, the elastic spring back potential of the material, and the distinct mechanical wear due to the highly abrasive carbon fibres. Therefore, this experimental study analyses different combinations of influencing factors with respect to process forces, workpiece surface temperatures at the wire entrance, and the surface quality in wire sawing unidirectional CFRP material. As main influencing factors, the cutting and feed speeds, the density of diamond grains on the wire, the workpiece thickness, and the fibre orientation of the CFRP material are analysed and discussed. For the tested parameter settings, it is found that while the influence of the grain density is negligible, workpiece thickness, cutting and feed speeds affect the process substantially. In addition, higher process forces and workpiece surface temperatures do not necessarily deteriorate the surface quality.


Sign in / Sign up

Export Citation Format

Share Document