Thermal shock resistance evaluation

Maensiri, S., Roberts, S.G. (2002), Thermal shock resistance of sintered alumina/silicon carbide nanocomposites evaluated by indentation techniques , J. Am. Ceram. Soc., 85(8), 1971-1978. 

Osterstock, F. (1993), Contact damage submitted to thermal shock a method to evaluate and simulate thermal shock resistance of brittle materials , Mater. Sci. Eng., A168, 41-44. 

Tancret, E, Osterstock, E (1997), The Vickers indentation technique used to evaluate thermal shock resistance of brittle materials , Scripta. Mater., 37(4), 443 447. 

As a result of evaluating the thermal shock resistance of graded type thermal barrier coating and its lifetime in a high-temperature oxidizing atmosphere, the following results were revealed. 

We proposed a new test method to evaluate the thermal shock resistance of epoxy resin (7). This test method uses a notched-disk specimen, and the thermal shock resistance can be evaluated analytically on the basis of linear fracture mechanics (8). In our previous studies, we reported on the use of our proposed thermal shock test and evaluation methods (8, 11) to determine the thermal shock resistance of toughened epoxy with a soft second phase (9, 10), and also with hard particulates (11). 

This chapter discusses the behavior, under thermal shock conditions, of epoxy resins toughened with ceramic particulates. Alumina Al203 and silica Si02, which are usually used as filler for insulation materials, and the new ceramic materials silicon carbide SiC and silicon nitride Si3N4 are employed. For these toughened epoxy resins, the thermal shock resistance is evaluated by using fracture mechanics. The difference between experimental and calculated values of the thermal shock resistance is discussed from a fractographic point of view. 

Evaluation of Thermal Shock Resistance. The results of the thermal shock tests are evaluated by the method based on fracture mechanics. Thermal shock resistance (ATc)cai, can be calculated as follows (8,10) ... 

The relationship between the ratio (ATc)exp/(ATc)cal and the volume fraction Vf is shown in Figure 9, where (ATc)exp is thermal shock resistance obtained by experiment. Where (ATc)exp/(ATc)cal = 1, it means that the thermal shock resistance can be evaluated well with equation 1. The thermal shock resistance of composites filled with silicon nitride, silica, and alumina can be especially evaluated at lower volume fractions. However, for silicon carbide, the ratio is not unity but greater than 1, and so the prediction of thermal shock resistance made with equation 1 is a conservative evaluation. In the case of alumina, on the other hand, the ratio (ATc)exp/(ATc)cal decreases remarkably with increasing Vf. These values of (ATc)exp/(ATc)cal are almost constant at lower volume fractions in every case. 

Because the alumina composites show (ATc)exp/ (A< 1, which indicates that the thermal shock resistance is overestimated by equation 1, the fracture behavior of alumina-filled composites is examined in further detail. As shown in Figure 7, debonding of the interface is observed in the thermal-shock test specimen but not in the fracture-toughness test specimen Therefore, for the evaluation of thermal shock resistance by equation 1 without overestimation, KIc should be measured under the condition in which the same fracture pattern as that seen in the thermal shock test is obtained. 

Table 32.8 compares the properties of AI2O3 to some of the other materials evaluated as candidate lamp-envelope materials. In addition to satisfying the materials selection criteria given above, AI2O3 also has a significant advantage over the other materials listed in Table 32.8 because it has superior thermal shock resistance. 

The thermal shock resistance ofunidirectionally reinforced SiC/RBSN composites was evaluated using the water quench method. Both room temperature flexural (Fig. 8) and tensile properties (Fig. 9) of 1-D SiC/RBSN composites were measured before and after quenching and compared with the flexural properties of quenched unreinforced RBSN under similar conditions. 

The thermal shock resistance of mullite-SiC whisker composites and mullite-Zr02-SiC whisker composites was evaluated by Kelly, et al. using samples prepared as described by Ruh andMazdiyasni. Thermal expansion, flexural strength and Young s modulus were... 

The present study aims at investigating the Reaction Bonded Silicon Carbide (RBSC) process to produce porous mullite-bonded SiC ceramics. Wu and Claussen (1991) reported a technique to produce mullite ceramics starting from Al, SiC and AI2O3 powder mixtures. However for the purpose of this study it was decided to use only SiC and Al 03 as the precursor powders with SiC as the major component so that after completion of the reaction the microstructure would be SiC bonded with mullite phase, with no residual alumina. This material was then tested for its mechanical properties like Young s modulus. Modulus of Rupture. Properties of Silicate-based SiC refractories have been reported to a certain extent by Reddy and others. Its potential use as a refractory material has been evaluated by measuring its thermal shock resistance. A sample refractory that has been designed in the... 

Alumina supports and catalysts were treated under conditions simulating the real processes, and various strength factors were determined [89]. As a result, a technique was designed for evaluating the thermal shock resistance, which... 

Amer. Ceram. Soc., 38,27,1955). A stack of ceramic rings, each 2 in. (50 mm) o.d. and 1 in. (25 mm) i.d., and V2 in. (12.5 mm) long, are heated from the inside by a heating element and cooled from the outside by a calorimetric chamber. Both thermal conductivity and thermal-shock resistance can be evaluated (cf. brittle-ring test). 

The selection of the thermal management materials for electronic packaging purposes demands close examination of thermophysical characteristics, such as thermal conductivity and diffusivity, specific heat capacity, coefficient of thermal expansion, and thermal shock resistance. A variety of measurement techniques have been developed to evaluate these properties, but this chapter focuses on thermal conductivity and diffusivity evaluation methods. Each of them is suitable for a limited range of materials, depending on the thermal properties and the medium temperature. The precise determination of the thermal properties of bulk composite materials is challenging. For instance, loss terms for the heat input intended to flow through the sample usually exist and can be difficult to quantify. 

Semler CE, Hawisher TH. Evaluation of thermal shock resistance of refractories using the ribbon burner method. Am Ceram Soc Bull 1980 59(7) 732. 

Plasma arc-jet and oxyacetylene torch ablation tests are much more convenient for operations and with much lower cost, which therefore are often used for primary evaluations of materials about their thermal shock resistance and ablation resistance properties . The difference between these two methods is their gaseous composition and flow speed. A plasma of air may exhibit ultra high temperatures above 5000°C and high velocities of 2 Mach but with ionized air atmosphere. On the other hand, the generally used oxyacetylene torch is of combustion gaseous products of carbon mono/dioxide, water vapor, OH and active hydrocarbon species with gas velocity less than 1 Mach and temperatures above 3000°C. A HVOF torch exhibits... 

Jian, C. Y., Hashida, T., Takahashi, H., and Saito, M., "Thermal Shock and Fatigue Resistance Evaluation of Functionally Graded Coatings for Gas Turbine Blades by Laser Heating Method," Composites Engineering, Vol. 5 (7), pp. 879-889,1995. 

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