No abstract

Kopsavilkums. Pētītas Latvija devona (Bāles atradne) un juras perioda (Skudras atradne) kvarca smiltis kā dispersās pucolāna piedevas betonam. Veikta abu atradņu smilšu smalcināšana ūdens vidē, noteikts mineraloģiskais, granulometriskais sastāvs un morfoloģija pirms un pēc smilšu smalcināšanas. Analizēta un izvērtēta dažāda granulometriskā sastāva smilšu pucolānu reakcijas aktivitāte, nosakot to kā brīvā kalcija hidroksīda daudzumu šķīdumā. Analizēts cementa pastas hidratācijas process atkarībā no Skudras un Bāles atradņu kvarca smilšu dispersitātes un apstrādes laika. Konstatēts, ka augstas dispersitātes Latvijas kvarca smiltīm piemīt pucolāna īpašības, tās veicina cementa pastas hidratācijas procesu un kristālisko kalcija hidrosilikātu veidošanos.

The new generation of high silica materials with high thermal resistance was created by leaching of chopped glass fibre. These materials with low thermal conductivity are inert to the majority of chemical reagents, resistant to organic and mineral acids, weak alkali, water and highpressure steam. High silica chopped strand mats are non-woven fabrics designed for using in a wide range of insulation and protection applications at temperature till 11000C. The technology and quality of leaching process of initial Si-Al-Na glass widely depends on quality of fibre surface characteristics, i.e., roughness of surface of glass filaments. The surface roughness of the fibre before leaching is a function of chemical durability, therefore it depend on content of Al2O3. The thermal conductivity (within 20…10000C) of chopped strand mats directly depends on the surface roughness. The morphology and compositional profiles of surface of glass fibre before and after leaching were investigated using AFM, SEM, X-ray microanalysis and X-ray powder diffractometer. The different defects for fibre with content of Al2O3 <2.5% and high roughness namely cracking and crystalline deposits of Na2SO4 on top and into pores of fiber after leaching have been identified. The presence of sodium ions on surface of fibre decreases the heat insulation properties of mats. The structure of glass filaments surface was investigated in order to clarify the influence of surface characteristics on thermal conductivity of high silica glass fibre non-woven fabrics.

Low melting zinc metaphosphate glasses

The article gives an overview of suitability of three kinds of phosphorus-containing glass systems: phosphate, alumosilicate phosphate and fluorophosphate for production of thick-films. Amorphous compositions based on metaphosphate glasses characterize high electric resistivity, thermal expansion coefficients matching with substrate, appropriate viscosity-temperature relationship, and suitable chemical reactivity, that they can be applied in thick-film technology for screen printed resistors on alumina substrate as an alternative of lead borosilicate glasses. Alumosilicate phosphate glasses are the base for the wide range of glass-crystalline high temperature materials (operating up to 10000C) for sealing of the silicon chip in microelectronics. Perfect adhesion of glass ceramics with substrate (the transition zone 5-7.5 μm) is provided by the formation of chemical bond with the oxidized surface of silicon and by the occurrence of analogous structural elements on the silicon surface and in the glass-ceramics. Due to the unique optical properties, low melting temperature of fluorine containing borophosphate glasses (FBP) can be used as brazing material (optical glue) for SiO2 glass optical fiber construction knots.