Thermal cycling resistance

Specifications and Test Methods. The American Society of Electroplated Plastics pubHshes a comprehensive book covering most technical aspects of testing and control (24). A number of ASTM standards have been issued that cover thickness, adhesion, and thermal-cycling resistance of the total plated film. Some specifically for plated plastics include ... 

The epoxy resin is a primary component in any epoxy adhesive formulation, and it is often referred to as the base polymer. However, it is certainly not the only or even not always the predominant component in influencing desirable end properties. Epoxy resins by themselves are often too rigid to provide the required properties such as flexibility, peel and impact strength, and thermal cycling resistance. As a result, they are often modified with other components or hybridized with other types of polymeric resins to provide these functions. 

The primary reactive diluents are monoepoxy low-molecular-weight epoxy resins. These may be used at rather high concentration with little effect on cured properties. Often they are employed to make selective improvements on certain properties such as adhesion, thermal cycling resistance, and impact strength. Some lower-viscosity commercial epoxy resins are already reduced with these diluents. 

The main advantages ofthe tubular design are good thermal cycles resistance and no requirement for high-temperature seals. In contrast, the planar geometry provides a higher volumetric power density. 

Thermal cycle resistance of Tic, TiC-Mo andTiC/Mo FGM coatings were investigated by the thermal cycling test of temperature range between room temperature and 1223K in 5 times ( heating, cooling speeds were 100 K/s ) in air. ... 

R. Tu and T. Goto, Thermal Cycle Resistance of Yttria Stabilized Zirconia Coatings Prepared by MO-CVD, Mater. Trans., 46, 1318-1323 (2005). 

Metal Supported-Solid Oxide Fuel Cells (MS-SOFC) represent a promising new design for fuel cells which may overcome the limitations of anode-supported cells (such as poor thermal cycling resistance and brittleness. Nickel phase re-oxidation upon exposure to transient uncontrolled conditions) due to the much better mechanical properties of the support that is represented by a porous thick metal substrate, the thickness of the ceramic layers (anode/electrolyte/cathode) being in the order of 10-50 pm, only. In addition, in this design (Fig. 1), the replacement of the thick Ni/YSZ cermet with ferritic stainless steel leads to several benefits in term of fabrication cost and safety. 

Nakano, F. Soga, T. Amagi, S. Resin-insertion effect on thermal cycle resistivity of flip chip mounted LSI devices. Proc. Inti. Soc. Hybrid Microelectronics (ISHM) 1987 536-541. 

Antimony may be added to copper-base alloys such as naval brass. Admiralty Metal, and leaded Muntz metal in amounts of 0.02—0.10% to prevent dezincification. Additions of antimony to ductile iron in an amount of 50 ppm, preferably with some cerium, can make the graphite fliUy nodular to the center of thick castings and when added to gray cast iron in the amount of 0.05%, antimony acts as a powerflil carbide stabilizer with an improvement in both the wear resistance and thermal cycling properties (26) (see Carbides). 

In such an environment an inner lining of acid-resistant brick is often used. Thermal cycling may also disrupt the film. Acid of more than 85 Vo concentration tends to dissolve the lead sulphate film, although lead has been used in cold quiescent conditions with concentrations of over 90 Vo. 

Cyclic Oxidation In many industrial applications it is particularly important for the component to be resistant to thermal shock for example, resistance-heating wires or blading for gas turbines. Chromia, and especially alumina, scales that form on nickel-base alloys are prone to spalling when thermally cycled as a result of the stress build-up arising from the mismatch in the thermal expansion coefficients of the oxide and the alloy as well as that derived from the growth process. A very useful compilation of data on the cyclic oxidation of about 40 superalloys in the temperature range 1 000-1 I50°C has been made by Barrett et... 

Under micro-discontinuous chromium coatings, copper undercoats improve corrosion resistance. On non-conductors, especially on plastic substrates, copper is often applied before nickel-chromium plating over the initial electroless copper or nickel deposit in order to improve ductility and adhesion, e.g. as tested by the standard thermal-cycling test methods ... 

Pure palladium becomes brittle in the presence of hydrogen during thermal cycling due to dimensional changes caused by a transformation between two phases (a and ft) of palladium hydride around 300°C. To avoid metal embrittlement and resulting membrane cracking or distortion, pure palladium membrane should not be exposed to hydrogen at temperatures below 300°C. To increase resistance to embrittlement, Pd is alloyed with... 

At relatively high temperatures thermocouple thermometers are most commonly used to measure temperature. The thermoelectric power of three frequently used thermocouples is compared in Figure 10.2. The choice of thermocouple depends on the temperature range, the chemistry of the problem in question, sensitivity requirements and resistance towards thermal cycling. The temperature range and typical uncertainty of some of the most commonly used thermocouple thermometers are given in Table 10.2. 

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