Determining the thermal conductivity of ceramic coatings by relative method

2019 ◽  
Vol 16 (6) ◽  
pp. 2299-2305 ◽  
Author(s):  
Dezhi Zheng ◽  
Yiwang Bao ◽  
Detian Wan ◽  
Shuai Yi
Keyword(s):  
Thermal Conductivity ◽  
Ceramic Coatings ◽  
Relative Method

Evaluating Mechanical Properties of Ceramics by Relative Methods

2007 ◽  
Vol 336-338 ◽  
pp. 2406-2410
Author(s):  
Yi Wang Bao ◽  
Xiao Xue Bu ◽  
Yan Chun Zhou ◽  
Li Zhong Liu
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Ceramic Coatings ◽  
Relative Method ◽  
Tempered Glass ◽  
Theoretic Analysis ◽  
Surface Strength ◽  
Indirect Approach ◽  
Before And After ◽  
The Relationship

A relative method, defined as indirect approach to evaluate the material properties via the relationship between unknown properties and a known property, is proposed to estimate some properties that could not be measured by the traditional methods for ceramics. Experiments and theoretic analysis based on the relative method were carried out in this study to estimate the properties in following aspects: determining the temperature dependence of elastic modulus of some machineable ceramics by comparing the deflections; obtaining the modulus and strength of ceramic coatings supported by substrates, from the variation in properties of the rectangular beam samples before and after coating; estimating the residual stresses in tempered glass by comparing the change in the surface strength after strengthening.

Granule spray process for fabrication of adherent, low thermal conductivity ceramic coatings

2021 ◽  
Author(s):  
Sae-Jung Yun ◽  
Jung Hwan Kim ◽  
Jongmoon Jang ◽  
Cheol-Woo Ahn ◽  
Woon-Ha Yoon ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Ceramic Coatings ◽  
Low Thermal Conductivity ◽  
Spray Process

Evaluating Thermal Expansion Coefficient of SiC Coatings by Relative Method

2017 ◽  
Vol 726 ◽  
pp. 110-114
Author(s):  
Rui Na Pan ◽  
Chen Guang Wei ◽  
Yi Wang Bao ◽  
De Tian Wan ◽  
Yan Ping Wang
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Ceramic Coatings ◽  
Test Method ◽  
Experimental Results ◽  
Simple Test ◽  
Relative Method ◽  
Novel Method ◽  
Sic Coatings

A simple test approach named relative method is developed for determining the thermal expansion coefficient of ceramic coatings. Although ceramic coatings are hardly separated from the substrates, it was evaluated in this work simply by need only the measured thermal expansion coefficient of coated samples and substrates. This novel method was demonstrated to be valid for rectangular beam samples of two types of coating configurations: sandwich coating and around coating. The feasibility of this test method was confirmed by experimental results of SiC coating.

Evaluating thermal expansion coefficient and density of ceramic coatings by relative method

2015 ◽  
Vol 161 ◽  
pp. 542-544 ◽  
Author(s):  
Chenguang Wei ◽  
Zhengquan Liu ◽  
Yiwang Bao ◽  
Detian Wan ◽  
Yan Qiu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Ceramic Coatings ◽  
Relative Method

Three-Dimensional Modeling of Reduced Material Properties in Ceramics With Added Porosity

2019 ◽  
Author(s):  
Stephanie A. Wimmer ◽  
Virginia G. DeGiorgi ◽  
Edward P. Gorzkowski ◽  
Heonjune Ryou
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Finite Element ◽  
Computational Modeling ◽  
Computational Models ◽  
Thermal Protection ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Ceramic Coatings ◽  
Grain Structure

Abstract Manufacturing methods to create ceramic coatings with tailored thermal conductivity are crucial to the development of thermal protection systems for many components including turbine blades in high temperature engines. A designed microstructure of grains, pores, and other defects can reduce the thermal conductivity of the ceramic. However, the same microstructure characteristics can reduce mechanical properties to the point of failure. This work is part of a larger program with the goal of optimizing ceramic coating microstructure for thermal protection while retaining sufficient mechanical strength for the intended application. Processing parameters have been examined to identify methods designed to maintain a nano-sized grain structure of yttria-stabilized zirconia while controlling the added porosity with a specific shape and size. In this paper computational modeling is used to evaluate the effects of porosity on coating performance, both thermal and structural. Coating porosity is incorporated in the computational models by randomly placing empty spaces or defects in the shape of spherical voids, oblate pores, or penny cracks. In addition to computational modeling, prototype coatings are developed in the laboratory with specific porosity. The size and orientation of defects in the computational modeling effort are statistically generated to match experiments. The locations of the defects are totally random. Finite element models are created which include various levels of porosity to calculate effective thermal and mechanical properties. Comparisons are made between three-dimensional finite-element simulations and measured data. The influences of pore size as well as three dimensional computational modeling artifacts are examined.

Determining Elastic Modulus of Ceramic Coatings at Elevated Temperature Using Impulse Excitation Technology

2016 ◽  
Vol 680 ◽  
pp. 13-16 ◽  
Author(s):  
Chen Guang Wei ◽  
Yi Wang Bao ◽  
Xue Qiang Cao ◽  
Zhao Liu ◽  
Yuan Tian
Keyword(s):  
Elastic Modulus ◽  
Elevated Temperature ◽  
Single Layer ◽  
Ceramic Coatings ◽  
Coated Sample ◽  
Multilayer Coatings ◽  
Relative Method ◽  
Impulse Excitation ◽  
Novel Method ◽  
Layer Coating

Although elastic modulus of ceramic coatings at elevated temperature is difficult to measure, it was evaluated in this work simply by impulse excitation tests based on the relative method that need only the measured moduli of coated sample and substrate. This novel method was demonstrated to be valid not only for the single layer coating but also for multilayer coatings.

scholarly journals On the thermal conductivity of gases by a relative method with an application to deuterium

1940 ◽  
Vol 175 (960) ◽  
pp. 36-48 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Constant Temperature ◽  
Gaseous Mixture ◽  
Wheatstone Bridge ◽  
Relative Method ◽  
Gaseous Mixtures ◽  
Heated Wire ◽  
In Series ◽  
Considerable Resistance ◽  
Deuterium Gas

The present paper is an account of a simple relative method of obtaining the thermal conductivity of a gas or a gaseous mixture to within 1 % for the complete range of gas conductivities. This is followed by an application of the method to deuterium gas. The principle of the apparatus to be described is similar to that upon which the so-called “conductivity meters” (e.g. the katharometer of G. A. Shakespeare, 1916-17) is based, but only in so far as both depend for their action on a transfer of heat from a heated wire through a surrounding gas. In the author’s apparatus this transfer takes place by conduction only but in the “conductivity meters” it takes place partly by conduction and partly by convection. The term “conductivity meter”, often applied to this and similar instruments, is misleading, for they do not and cannot measure the thermal conductivity of a gas or gaseous mixture. Calibrated empirically in terms of gaseous mixtures of known composition they are used industrially in the investigation of composition of other mixtures. Generally these industrial meters employ two similar fine metal filaments of considerable resistance (often 10-20 Ω ) connected in series and placed in the adjacent arms of a Wheatstone bridge. They are mounted in some form of cell designed for working at a constant temperature and either wire can be surrounded by any selected gas or mixture.

scholarly journals Evaluating high temperature elastic modulus of ceramic coatings by relative method

2017 ◽  
Vol 6 (4) ◽  
pp. 288-303 ◽  
Author(s):  
Guanglin Nie ◽  
Yiwang Bao ◽  
Detian Wan ◽  
Yuan Tian
Keyword(s):  
Elastic Modulus ◽  
High Temperature ◽  
Ceramic Coatings ◽  
Relative Method
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