The surface structure of aluminum porcelain enamel was affected considerably by the firing temperature and time.
The results obtained by X-ray diffraction methods showed that the relative intensities of diffractions from the face (111) of PbO⋅TiO₂ (perovskite structure) and the face (222) of 3PbO⋅Sb₂O₅ (pseudo-face centred cubic structure) depositted in the coating on a sheet of aluminum were abnormally strong. It is supposed that these faces are paralleled to the original aluminum surface.
A hexagonal crystal of PbO⋅TiO₂ of corundum structure was obtained when small amount of V₂O₅ was added in a frit composition.
The diffractions from both faces of (0006) and (0004) were also abnormally strong. These facts suggested that these faces might be paralleled to the original aluminum surface. The hexagonal lattice of the face (0006) was equivalent to the face (111) of cubic lattice as shown in Fig. 6.
In any case, it was found that the face (111) of PbO⋅TiO₂, (222) of 3PbO⋅Sb₂O₅, (0004) or (0006) of hexagonal type corresponded to the close-packed planes of oxygens, and they were paralleled to the surface of the porcelain enamel.

抄録全体を表示

The effect of particle size distribution on the ceramic properties of wet ball-milled Nishiyama pottery-stone which world be used on ceramic whiteware were investigated.
The milling was carried out under 5 different conditions to give the particles whose specific surface area covers from 1.225 to 1.662m²/g. Also the sample containing the particle under 10 microns obtained by elutriating after milling was studied. And these were fired at 1000°, 1050°, 1100°, 1150° and 1200°C and measured for various fired properties.
The results obtained are summarized as follows:
(1) Nishiyama pottery-stone is essentially composed of albite, orthoclase, quartz and small amounts of clay minerals. Feldspar minerals, especially albite, were easy to grind but quartz was not.
(2) Surface area increased at first linearly as the ball-milling time increased but with the elaps of time the rate of increase showed considerable decrease.
(3) The concentrated slips prepared by this way resembled the rheological behavior of Newtonean flow, but showed dilatancy when the deflocculant was added. The effect of deflocculant on viscosity is influenced by the amounts of coarse grain.
(4) The effect of the aging of slip on the variation of viscosity was the least in case specific surface area was 1.4m²/g.
(5) The finer the grains the less is the thermal expansion of green body.
(6) During the immatured firing range the firing shrinkage and bulk specific gravity were influenced by grain size but in maturing temperatures such properties were affected by specific surface area.
(7) The modulus of rupture of the fired specimens was influenced by grain size, and independed to the specific surface area.
(8) During the immatured firing range the thermal expansions increased as the amounts of coarse grain increased, while in maturing temperatures they were decreased.
(9) It was found no relation between the reflection and the grain size of fired specimens.

抄録全体を表示

Silica glass, owing to its high thermal endurance, is used for bulbs of high pressure mercury discharge lamps, xenon discharge lamps or incandescent iodine lamps. Thermal expansion of silica glass is so low that metals or alloys with comparably low expansion coefficients to seal with are not found. Sealing with thin molybdenum foils is an usual technique in lamp manufacturing industry. Stresses in such a seal caused by expansion difference between metal and glass are reduced by plastic flow of the foil.
Stresses in experimental seals were studied photoelastically. Foils used were 20μ thick. Severe and mild stress concentrations in glass were observed near the edge and the surface of foil respectively. Change of distribution of stresses with temperature was rather complicated, showing some hysteresis phenomena caused by plastic and elastic deformation of foil and viscous flow of glass. Stresses in glass were evaluated to be less than 1kg/mm² except near the edge of foil. Effect of plasticity of foil on distribution or reduction of stresses were discussed.

抄録全体を表示