In general, steel enamel is fired at a temperature higher than 820°C in order to make it sufficiently resistant to heat and corrosion. If only it has an excellent chemical durability, however, for some use being required not so much high thermal resistance, one can easily understand that firing at a temperature much lower than that for the conventional steel enamel should be economically much more profitable. Development of such a steel enamel is expected by studying on an enamel having a strong adhesiveness between the metal and the cover coat fired with some low melting frit which is anticipated to be obtained by using a phosphate frit having a high chemical durability in spite of its low fusibility.
In the present study a phosphate glass developed at our laboratory as a chemical resistant frit for aluminum enamel was used as a frit for such a steel enamel fired at a low temperature. And then, as the pretreatment for steel plate, the following treatments were tested, i.e., pickling in hydrochloric, sulfuric, or nitric acid, parkerizing, nickel-dip, and anodic oxidation.
Relation between the adhesiveness of enamel and the bonding mechanism ocurring at the glass-steel interface was investigated by discussing the experimental results obtained from bending tests for the enamel specimens under tension and surface texture diagrams of the pretreated metal which were drawn by Talysurf's roughness tester.
It was concluded as follows:
1) Adhesion of the low melting glass to steel was considered to attribute mostly to mechanical bonding rather than the other chemical causes.
2) The enamel with fairly high adhesiveness could be obtained even when the steel plate was only pickled in 20% nitric acid. It was likely to be not any clear relation between the roughness in “centre line average H_CLA (index number of texture)” of metal surface and the adhesiveness of enamel expressed by the angle which was measured by the bending test under tesion. It was confirmed, however, that there was a linear relation between the texture frequency and the adhesiveness. The good adhesiveness was given under the following condition of pickling, i.e., 20% nitric acid, bath temperature 16°±1°C or 25°±1°C, and treating time 30-60 sec. or 15 sec., respectively.
3) In case of nickel-dip treatment, the obtained enamel displayed a excellent adhesiveness on account of an effective action of nickel, that is to say, nickel depositing on the steel surface in this case effectively protected the metal surface against oxidation during firing. The optimum condition in the way of such a pretreatment was as follows: dipping in 20% nickel sulphate solution at 16°±1°C for 10-20min. In the opposite way, in both cases of anodic oxidation and parkerizing treatments, the adhesiveness of enamel lowered with prolonging time of treatment.
4) The optimum condition of firing at a low temperature for this kind of steel enamel was found to be fired at 550°±10°C for 15-30 sec.

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The sintering process of the AIN-Al system in N₂ gas was observed employing high tem perature X-ray diffraction, and the mechanism of sintering was investigated.
Nitriding reaction of Al began at 580°-600°C. The temperature of the powder compact of AlN-Al rose rapidly by nitriding reaction of Al, due to the exothermic nature of nitriding reaction of Al (ΔH₂₉₈=-76.4kcal/mole). When the temperature of the sample exceeded the melting point of Al (660°C) because of the said exothermic reaction, a few Al particles not having reacted with nitrogen became viscous and aggregated with other Al particles, and for this reason the sintered product became heterogeneous. When a sample was heated to the temperature around or above the melting point of Al before nitriding, Al particles because of the same reason as above flew out to the surface of the sample.
In order to apply these results to production, the effects of the forms and Al contents of the crucible shaped samples on sintering were tested.
Based upon the above experiments and discussion the sintering condition of AlN-Al was determined.

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In order to produce single crystals of Mg(OH)₂ larger than those usually synthetically obtainable, experiments were conducted under the following condition:
Reactants: Aqueous solution of Mg nitrate, sulfate or chloride, and of the hydroxides of Na and Ca.
Concentrations: Always equal for the two reactants, being 1/10, 1/20, 1/30, 1/40 N and N/50 in the case of NaOH, and 1/40, 1/50, 1/100 N for Ca(OH)₂.
Temperatures: 34.5, 40, 50, 60, 70, 75.7, 79.5°C.
Mother liquor: Stagnant distilled water.
Addition rates of the reactants: 0.5-3.0cc/hr, through two porous ceramic membranes, the pores of which had an average diameter of 0.5μ.
Overall times of addition: 5 to 40 days of continuous diffusion under fixed conditions.
The principal results can be summerized as:
1) The anions and cations accompaning the main species involved (Mg²⁺ and OH^-) have no large effect.
2) Temperatures above 60°C, both the size and shape of the produced single crystals improve greatly.
3) Better and large single crystals are produced by reactants N/50-N/30 in concentration.
Optimal rates of addition into distilled water are V/800-V/600 per hour (V=volume of mother liquor).
Combining the last two statements, the best results were obtained at (3.5-7.7) 10^-12V⋅Mol⋅sec^-1.
4) Optimal diffusion times 7-14 days. Below this period no good large crystals were obtained, and longer times did not improve these any further.
5) Best results were obtained with final pH values within 9.5-10.8.
6) Under the best combination of the conditions detailed in (1) to (5) above, well defined single crystals of Mg(OH)₂ 140 to 400μ were produced.
7) The yields of crystals larger than 20μ reached 30-77%.

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ZnO単結晶は, 超音波増幅素子としての応用が考えられており, その水熱育成でLiをドープしたZnOとCuをドープした未発表のZnO単結晶との晶癖において顕著な相違を認めた. LiドープZnO: c軸方向の成長率が抑えられ, -c (0001) 及びp (1011) 面の発達が著しいいわゆるピラミッド型となる (Fig. 1). CuドープZnO: 逆にc軸方向の成長率が促進され, m (1010) 面の発達が顕著で柱状となる (Fig. 2). 電気抵抗率はLiドープZnOとCuドープZnOとはほとんど等しく, 10³-10⁵Ω-cmの値をとる. この値は超音波増幅素子として利用出来得る値である. CuドープZnOの中のCuの定量はまだ行なっていないが, 抵抗率の値からLiドープZnOで検討されたLi⁺アクセプターと同様にCu⁺アクセプターの作用でこの抵抗率の補償が行なわれているものと考える. この補償と同時にc方向の成長率がLiドープZnOより増大させ得ることは, 超音波増幅の縦波用素子として有用であり, 結晶の晶癖と電気抵抗率のコントロールが行なえ得ることは興味あることである.

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