In order to examine the change of composition in the matrix of fire clay refractory during heating, the reaction between α-Al₂O₃ containing mullite particle and Na₂O⋅2SiO₂ glass was studied with varied temperatures from I hr to 96 hrs.
Obtained results were as follows;
1) The dissolution process of mullite into glass is the first order reaction in the heating procedure of 36-64 hrs and its activation energy was ca. 50kcal/mol. In the case of longer heating time, diffusion rate of mullite particle into glass was saturated.
2) The content of α-Al₂O₃ in the particle increased slightly with the heating time.
3) In the process of reaction between mullite particle and Na₂O⋅2SiO₂ glass, both nephelite and carnegieite deposited. The amout of nephelite decreased with the rise of temperature, but that of carnegieite was affected by the amount of Na₂O⋅2SiO₂ glass and heating temperature.
Especially, the less the amount of glass added, the more the amount of carnegieite increased with the heating temperature.

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In this report, the growth of β-SiC crystal by gaseous phase reactions between silicon tetrachloride and toluene with hydrogen used as a carrier gas on the surface of a heated graphite substrate at high temperatures was investigated.
The deposits was prepared under the condition in which the molar ratio of silicon tetrachloride to toluene was maintained between 4:1 and 1.3:1, on a graphite substrate heated by H. F. induction furnace at the temperature up to 1500°C. Several variations of deposition and crystal forms of β-SiC relating to the gas flow rate and molar ratio of silicon tetrachloride to toluene were observed in this experiment.
The beta-silicon carbide deposits which grew in an atmosphere with the proportion of 3.5:1 to 2.5:1 of silicon tetrachloride to toluene, consisted of transparent yellow and prism shaped crystals and it was found that the decrease in the molar ratio from 2.0 resulted in the formation of colorless and triangular crystals.
The characteristics of these deposits by vapor phase reaction method at high temperatures were determined by optical observations and X-ray powder diffraction analysis.

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The distribution of pressure in a specimen chamber of a simple squeezer was estimated by using the change in refractive index of quartz glass with pressure as a pressure calibrant. The relation between the refractive index of the glass and pressure can be represented by the following epuation
N_p=1.461+ap+bp²,
where N_p is the refractive index of quartz glass at 22°C after the compression under pressure p kb, a and b are numerical constants and are 4.0×10^-4 and 4.8×10^-6, respectively. The distribution of the refractive index in the specimen chamber was measured at room temperature not only in the radial direction but also in the axial direction.
The radial distribution of pressure estimated from the refractive index distribution agreed well with that obtained by using the Bi_I-II transition point. The pressure in the central part of specimen chamber was 1.5 times greater than the pressure in the peripheral part when a stainless steel ring of diameter to thickness ratio of 22.4:1 was used.
In order to estimate the pressure distribution at higher temperatures, quartz glass powder was treated with water at 500°C, under pressure of 21kb and 20kb measured at the central part of the specimen.
Under 21kb, all glass powder changed to coesite in the central part of the specimen chamber and quartz was found along with coesite in the peripheral part, while under 20kb glass powder in the central part changed mostly to quartz and partially to coesite, and only quartz was observed in the peripheral part.
The temperature distribution was measured by thermocouple placed in the central and the peripheral part of the specimen and adjacent to the outside of the ring. Only a small difference in temperature was observed in the specimen chamber.

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ZrB₂ was hot-pressed at the temperature range from 1450° to 1970°C with or without additions of 6% of metallic binders- Cr or Ni. Densification rates at constant pressure of 200kg/cm² were measured continuously for about 30 min at each test temperature.
For the hot-pressing below the melting temperature of metallicbin der, these data were treated reasonably with following equation which were proposed by Murray et al. for the plastic flow model of hot-pressing ceramics.
dD/dt=(3P/4η)(1-D) and integrating,
ln(1-D)=-(3P/4η)t+ln (1-D₀).
Viscosity, η, was calculated at various temperatures for ZrB₂ compacts. Activation energy was about 85kcal/mol.
In case when ZrB₂-metal mixtures were hot-pressed above melting temperatures of metals, porous surface layers were observed with deficiency in metallic binder and with deviation of densification data from Murray's epuation.

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