Cooling, after sintering

Because nanocomposites are made from different phases with different thermal expansion coefficients and elastic moduli, they inevitably develop residual thermal stress during cooling after sintering. Assuming the dispersion phase is spherical particulate in the matrix material, residual stresses can be developed due to differences in the thermal expansion and elastic constants between the matrix and the particles [23] ... 

Consider a ceramic-metal FGM which undergoes a thermal load history as shown in figure 1. The thermal loading history consists of two phases phase I corresponds to the cooling after sintering(processing phase), the stress in this phase is called residual stress phase II... 

Eor processing after sintering, in the least expensive method for sintered PTEE tape or sheet, a large billet is skived on a lathe after it has been sintered and cooled. High precision articles are machined from ram-extmded rods. 

Lead (II) chloride [7758-95-4] M 278.1, m 501°. Crystallised from distilled water at 100° (33mL/g) after filtering through sintered-glass and adding a few drops of HCl, by cooling. After three crystns the solid was dried under vacuum or under anhydrous HCl vapour by heating slowly to 400°. 

Upon the addition of ethanolic HCI to a solution, cooled to 0°C, of 26.38 parts of the free base in 130 parts by volume of absolute ethanol, until a Congo-acid reaction is achieved, the crystalline dihydrochloride of 3-ethylmercapto-10-[3 -(1 "-methyl-piperazyl-4")-propyl-1 ] -phenothiazine is precipitated. The analytically pure salt has a melting point of 214°C to 216°C (bubbles) it begins to sinter at 205°C. The dimaleate melts at 188°C to 190°C after sintering from 180°C (recrystallized from methanol). 

At the end of the firing schedule, the cylindrical furnace is cooled, the quartz column is removed, and the actinide oxide microspheres are transferred by pouring into the platinum-lined crucible. The open-top crucible is placed in a muffle furnace and the oxide is sintered at about 1050°C for 16 h. Although there is no forced air flow during the sintering step, the approximately 10-mm-deep bed of oxide is exposed to air inside the furnace. After sintering has been completed, the oxide is cooled prior to the oxide characterization steps. 

In the sintering of AI2O3 a small amount of SiO, some 5%, is used to lower the sintering temperature from near 1600 to 1400°C due to a low melting eutectic at 1587°C. After sintering is complete, calculate the amount of mullite present in the sample. Explain why cooling this sample will be problematic. 

The combined filtrate and washings from the piperazine dihydrochloride are cooled in an ice bath and treated with 25 ml. of absolute ethanol saturated at 0° with dry hydrogen chloride (Note 3). After the solution has been well mixed, it is cooled for 10-15 minutes in an ice bath. The precipitated white plates of 1-benzylpiperazine dUiydrochloiide are collected by suction filtration, washed with dry benzene, and dried. The product, which melts at about 280° with decomposition, after sintering at about 254° (Note 4), amounts to 29.0-29.5 g. (93-95%). A solution of this salt in 50 ml. of water is made alkaline (pH >12) with about 60 ml. of SA sodium hydroxide, then extracted twelve times with 20-ml. portions (Note 5) of chloroform. The combined extracts are dried over anhydrous sodium sulfate, and the pale-brown oil (Note 6) remaining after removal of solvent is distilled at reduced pressure in a Claisen flask. The yield of pure 1-benzylpiperazine, b.p. 122-124°/2.S mm., d 1.5440-1.5450, is 14.3-16.5 g. (65-75%). 

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