Glass and Ceramics最新文献

This articles discusses the use of 20Kh23N18T mark stainless steel and its foreign analogue AISI 310S instead of 12Kh18N10T steel as a material for making shaping dies used in the manufacture of glass insulators made from S93-3M mark electrovacuum glass. Such insulators are widely used in the radio-electronic industry as housings for magnetically operated contacts. It is shown that at operating temperatures a chemical interaction occurs between both grades of steel and S93-3M grade glass, which results in deterioration in the product quality on account of the appearance of a large number of gas bubbles in the product. It was ascertained that the additional heat treatment makes it possible to diminish the consequences of this chemical interaction, and thereby improve the quality of the resulting product.

The development of an original practical method of estimating the specific energy to failure of ceramic compositions in the system abrasive grain–ceramic binder–pores system is described. The results of experimental investigations and theoretical calculations, on which the method proposed by the authors is based, are presented. Recommendations for its use are given.

Atechnology of glass-concrete was developed based on dispersed container and sheet glasses. It is shown that on joint grinding of Portland cement and cullet at specific surface area of 5890 – 6450 cm²/g, particle size 3.4 – 3.6 μm, and weight content of dispersed glass in the composite equal to 20 – 50% with hyper-plasticizer the glass-concrete corresponds to classes B30 – B40, which meets the requirements of regulatory documents. The microstructure of glass-concrete and the features of its dehydration on heating to 1000°C were investigated. It was ascertained by means of x-ray phase analysis that sodium-calcium hydro-aluminosilicates such as gmelinite and thomsonite are formed in glass concrete.

A method is proposed for processing the back side of silicon transistor structures before metallization [metal deposition] and before contact to the transistor is made. The parameters of the surface roughness of a silicon surface treated with silicon carbide sand were investigated so as to improve the adhesion properties before contact deposition is made to the collector region of a transistor.

Hydroxyapatite (HA) Ca₁₀(PO₄)₆(OH)₂ powders kept for 1 h with stirring in 0.25 M aqueous solutions of dihydrogen phosphates of ammonium NH₄H₂PO₄, sodium NaH₂PO₄, and potassium KH₂PO₄ were used to obtain ceramics. According to XRD data, there were no changes in the phase compositions of powders after such treatment. After firing at 900 – 1100°C the phase composition of ceramics based on HA Ca₁₀(PO₄)₆(OH)₂ powder treated with an aqueous solution of NH₄H₂PO₄ included β-tricalcium phosphate β-Ca₃(PO₄)₂ and HA Ca₁₀(PO₄)₆(OH)₂; the phase composition of ceramics based on HA powder Ca₁₀(PO₄)₆(OH)₂ treated with an aqueous solution of NaH₂PO₄ included sodium-substituted tricalcium phosphate Ca₁₀Na(PO₄)₇ and HA Ca₁₀(PO₄)₆(OH)₂; the phase composition of ceramics based on HA powder Ca₁₀(PO₄)₆(OH)₂ treated with an aqueous solution of KH₂PO₄ included potassium-substituted tricalcium phosphate Ca₁₀K(PO₄)₇ and HA Ca₁₀(PO₄)₆(OH)₂. The formation of biphasic ceramics occurred because of reduction in the Ca/P molar ratio of HA Ca₁₀(PO₄)₆(OH)₂ powder after treatment in aqueous solutions of dihydrogen phosphates of ammonium NH₄H₂PO₄, sodium NaH₂PO₄, and potassium KH₂PO₄. Adsorption of cations and anions from solutions on the surface of HA particles, slight dissolution of HA in aqueous solutions of dihydrogen phosphates with acidic pH, as well as ion exchange of cations and anions in the HA structure for cations and anions from solutions were possible processes effecting change in the ratio of cations and anions in HA powder. The resulting ceramic composites contain biocompatible phases and can be recommended for creating bone implants.

Features of the thermoelectric properties and microstructure of composites with a matrix based on Bi₂Te_2.7Se_0.3 and an Fe filler were ascertained. A composition with filler weight content 0.3% Fe has a higher quality factor ZT compared to the Bi₂Te_2.7Se_0.3 matrix. For this composition the maximum value of ZT reaches about 0.75, while for Bi₂Te_2.7Se_0.3 ZT does not exceed about 0.63. So, in a composite of the system Bi₂Te_2.7Se_0.3 + Fe the thermoelectric quality factor can be increased by about 20%.

The technology of facing material based on mechanically activated cullet modified with sodium hydroxides has been developed. The phase composition, macro- and microstructure of the lining material are investigated. It is established that the microstructure of a composite modified with sodium hydroxide in the interpore space is represented by lamellar crystals of sodium meta-, di and orthosilicates. The optimal composition for obtaining a facing material with a compressive strength of 24.7 MPa and a softening coefficient of 0.91 has been established.

The results of studying the effect of filamentary striae with birefringence 3 to 15 nm/cm in sitall [glass-ceramic] SO-115M on the quality of manufacturing of optical components of ring lasers and the accuracy characteristics of laser gyroscopes based on them are presented. It is shown that the presence of streaks with stresses not exceeding 15 nm/cm in sitall SO-115M does not affect the manufacturing accuracy of the resonator optical circuit and its assembly quality. The streaks in the output mirror of a ring laser serve as a source of additional backscattering and can increase the lock-in zone width. Proper adjustment of the output mirror makes it possible to reduce the amount of scattering and minimize the growth of the lock-in zone in a laser gyroscope. It is shown that the accuracy of a laser gyroscope is determined by the quality of the mirror substrates, the body geometry, and the level of backscattering inside the resonator.