Coefficient of thermal expansion, table

Glass-fibre-filled polysulphones are also available. These show significantly increased creep resistance and lower coefficients of thermal expansion (Table 21.4). 

Zirconia (Zr02) has the stiffness of steel, a density which is only 50% higher than that of alumina, a relatively high coefficient of thermal expansion (Table I) and excellent chemical... 

Pu is a typically silver-white appearing metal which has a number of peculiar physical properties. The metal undergoes a total of five allotrppic modifications below the melting point, two of which have negative coefficients of thermal expansion. Table IV-1 summarizes the more important physical properties. 

There is little to be gained by using relatively large, two-terminal devices on thermoplastic materials. Two-terminal devices such as chip resistors are based on ceramic bodies, and consequently they have extremely low coefficients of thermal expansion (Table 5.1). The difference in CTE vis- -vis the thermoplastic substrate material is highest for this type of component. Given the absence of conditionally elastic connector legs, this type of device is extremely stiff and consequently unable to prevent deformation at the point of connection. 

The polymer matrix used in this study is that of a family of Polyethablockamides known by the trade name Pebax. The grade used was that of Pebax 7033. The data required for the analysis include the yield stress, yield strain, initial modulus, secondary modulus, ultimate stress and ultimate strain. Other data needed is the Poisson s ratio and linear coefficient of thermal expansion. Table 1 lists the relevant properties. 

This table lists values of /3, the cubical coefficient of thermal expansion, taken from Essentials of Quantitative Analysis, by Benedetti-Pichler, and from various other sources. The value of /3 represents the relative increases in volume for a change in temperature of 1°C at temperatures in the vicinity of 25°C, and is equal to 3 a, where a is the linear coefficient of thermal expansion. Data are given for the types of glass from which volumetic apparatus is most commonly made, and also for some other materials which have been or may be used in the fabrication of apparatus employed in analytical work. 

The typical mechanical properties that qualify PCTFE as a unique engineering thermoplastic are provided ia Table 1 the cryogenic mechanical properties are recorded ia Table 2. Other unique aspects of PCTFE are resistance to cold flow due to high compressive strength, and low coefficient of thermal expansion over a wide temperature range. 

Table 7 gives the composition of gold alloys available for commercial use. The average coefficient of thermal expansion for the first six alloys Hsted is (14-15) X 10 j° C from room temperature to ca 1000°C two opaque porcelains used with them have thermal coefficient expansion of 6.45 and 7.88 X 10 from room temperature to 820°C (91). The HV values of these alloys are 109—193, and the tensile strengths are 464—509 MPa (67-74 X 10 psi). For the last four alloys in Table 7, the HV values are 102—216, and the tensile strengths are 358—662 MPa (52-96 x 10 psi), depending upon thermal history. 

No tables of the coefficients of thermal expansion of gases are given in this edition. The coefficient at constant pressure, l/t)(3 0/3T)p for an ideal gas is merely the reciprocal of the absolute temperature. For a real gas or liquid, both it and the coefficient at constant volume, 1/p (3p/3T),, should be calculated either from the equation of state or from tabulated PVT data. 

TABLE 28-4 Coefficient of Thermal Expansion of Common Alloys ... 

The coefficient of thermal expansion of 316 stainless steel is 9.7 x 1()- in/in per degree Fahrenheit. The metric equivalent is 17.5 x 10 <> mm/mm. per degree Centigrade. See the next Table and note the expansion on a pump whose eenterline is 10 inch above its base. 

A key factor in the suitabihty of cokes for graphite production is their isotropy as determined by the coefficient of thermal expansion. After the calcined coke was manufactured into graphite, the axial CTE values of the graphite test bars were determined using a capacitance bridge method over a temperature range of 25 to 100°C. The results are summarized in Table 24. Also included in the table are bulk density measurement of calcined cokes and the resistivity values of their graphites. 

The other principal thermal properties of plastics which are relevant to design are thermal conductivity and coefficient of thermal expansion. Compared with most materials, plastics offer very low values of thermal conductivity, particularly if they are foamed. Fig. 1.10 shows comparisons between the thermal conductivity of a selection of metals, plastics and building materials. In contrast to their low conductivity, plastics have high coefficients of expansion when compared with metals. This is illustrated in Fig. 1.11 and Table 1.8 gives fuller information on the thermal properties of pl tics and metals. 

There are standard procedures for determining aj (e.g. ASTM 696) and typical values for plastics are given in Table 1.2. It may be observed that the coefficients of thermal expansion for plastics are higher than those for metals. Thus if 50 mm lengths of polypropylene and stainless steel are each heated up by 60°C the changes in length would be... 

Thermal expansion — as elasticity — depends directly upon the strength of the intermolecular forces in the material. Strongly bonded materials usually expand little when heated, whereas the expansion of weak materials may be a hundred times as large. This general trend is confirmed by Table 5.1. The coefficient of thermal expansion a was found to be lower in the crosslinked polymers and higher in the less crosslinked or thermoplastic materials as observed by Nielsen [1], In addition, Table 5.1 presents the Young s moduli E of the polymers at ambient temperatures as well as the products a2E. The values of oc2E are all close to 13.1 Pa K 2 with a coefficient of variation of 1.6%. 

The main characteristic of refractory oxides is their excellent resistance to oxidation. Their brittleness however makes them prone to thermal shock with the exception of silica which has a compensating low coefficient of thermal expansion. The chemical resistance of the major oxides deposited by CVD is rated in Table 17.7. 

Case 2. For data sets that do not meet the criteria of Case 1, but contain acceptable values over a temperature range of at least two degrees, the results are smoothed using a linear function of temperature with an estimated coefficient of thermal expansion. A table of smoothed recommended values is presented. 

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