Highly refractory unfired products with a magnesium-phosphate bond

Conclusions In laboratory conditions compositions were tested for making (by the semi-dry method) refractory articles based on fused magnesite with a bond made from magnesium monosubstituted phosphate.These unfired articles have high strength and spalling resistance.The properties of the developed unfired bodies made from fused magnesia can be recommended primarily for making highly refractory ramming linings and articles (including heat-resistant tubes) for high-temperature furnaces of the laboratory type.     

固体磷酸铝结合高强度刚玉浇注料的研制

采用市售固体磷酸铝和刚玉原料 ,加入0 .75 %～ 1 .2 5%的硬化剂MgO ,0 .0 5 %～ 0 .1 5 %的抑制剂NH ,研制的固体磷酸铝结合高强度耐火浇注料 ,具有常温固化 ,施工简便 ,施工性优良 ,可以快速进行热处理的特点。适量的硬化剂可以促使磷酸铝常温固化 ,抑制结合剂的迁移 ,提高材料的整体结合强度 ;加入抑制剂可以抑制酸铁反应 ,避免发生膨胀 ,提高浇注料的强度     

Highly refractory mortar for bonding corundum refractory

Conclusions The composition of corundum mortar based on 80% corundum aggregates fractions <0.5 mm and 20% finely milled processed alumina was established. In order to prepare a wet mortar we incorporated 10% orthophosphoric acid, and 0.1% plasticizing addition of sulfite lye.The mortar of this composition will set at low temperatures, maintaining the necessary working properties in a wide heating temperature range.Translated from Ogneupory, No. 8, pp. 40–43, August, 1970.     

铝合金熔化炉熔池内衬刚玉瘤成因及对策

铝合金熔化炉熔池内衬刚玉瘤的形成与扩展是熔池内衬耐火材料破损的重要原因.铝合金熔化炉熔池内衬耐火浇注料和刚玉瘤的化学分析结果显示,刚玉瘤中Al2O3的质量分数为94％,远高于原浇注料的61.0％.分析认为,铝及其合金元素与耐火材料间的化学反应,铝液液面的氧化反应,炉内温度过高是刚玉瘤形成的原因,而且冶炼过程中加入的助熔剂或清渣剂加速了对内衬耐火材料的渗透.据此提出了降低刚玉瘤形成及减轻内衬损毁的对策.     

Use of thermal-shock resistant electric-insulating phosphate ceramics based on corundum for making high-temperature tensosensors

Conclusions On the basis of the results of a study of the temperature dependence of the resistance of insulation and the tensometric sensitivity of sensors, and an evaluation of the adhesion and thermal-shock resistance of ceramic material KPN-3, it can be expected that the use of this material for making high-temperature tensosensors will increase the application limits (as regards the properties of the bond) to a temperature of about 800°C.Repeat cyclic heating of the coating KPN-3 to 850°C not only does not reduce its electrical insulating properties, but somewhat increases them. The continuity of the material and its adhesion properties are also preserved.Translated from Ogneupory, No. 5, pp. 59–61, May, 1971.     

Sialon结合刚玉耐火材料的制备

利用天然高岭土通过碳热还原氮化法合成β′-Sialon（Si2Al3O3N5）粉体，并制备出Sialon结合刚玉耐火材料。Sialon结合刚玉耐火材料可在1550～1640℃烧结，烧结体的体积密度为3．10g·cm－3，气孔率21％，抗折强度85．0MPa，900℃冷水淬冷10次制品仍保持原有强度，1350℃空气流中重量增加低于0．30％。     

Low-cement castables of corundum and aluminum compositions

The effect of the mineral and grain composition of charges and the manufacturing technology and characteristics of vibroshaping of low-cement thixotropic castables having an alumosilicate and a corundum composition on the physicochemical properties of the obtained material are considered. Experimental refractories fabricated of low-cement castables have been tested in intermediate ladles of a continuous casting machine. The developed low-cement thixotropic castables possess high physicomechanical and operational properties and can be used in various metallurgical equipment.     

Rapid drying cycle for corundum insulating products

Conclusions A drying cycle was developed for corundum insulating brick in metal molds directly after casting. The drying time was reduced by a factor of 7.Translated from Ogneupory, No.5, pp. 16–17, May, 1970.     

Porous materials based on corundum and aluminophosphate bond

Conclusions Highly porous corundum products obtained by using fluoroplastics have a relatively high strength in the green state (7 kg/cm² with an apparent density of 0.4 g/cm³), and a low apparent density after firing (0.23 g/cm³).The incorporation of aluminophosphate bond sharply increases the strength of the products after combustion of the organic part, and reduces the total shrinkage during heat processing from 30 to 4–5%.The use of electrofused corundum in place of commercial alumina reduces the concentration of organic constituent in the body to 18%; under these conditions the additional shrinkage at 1600°C of specimens fixed at 1000°C drops to 0.5–1%.Translated from Ogneupory,No.5, pp.46–50, May, 1972.     

Use of partially acidulated phosphate rocks as phosphate fertilizers

Partially acidulated phosphate rocks (PAPRs) are manufactured by acidulation of PRs with less than the stoichiometric amounts of, usually, phosphoric or sulphuric acids. Products of similar composition to PAPRs are also prepared by cogranulating superphosphate with PRs. For most crops the agronomic value of PAPRs is determined by the availability to plants of their water-soluble P as well as their PR P component. The acid unreacted PR present in the directly acidulated PAPR, is considered to be less reactive than the original PR. This is probably the result of surface coatings of chemical compounds formed during acidulation. Under some soil conditions, in the presence of plants, the PR component probably dissolves faster than the original PR. For seasonal crops, except for fast growing ones such as squash (Cucurbita maxima), reactive PRs partially acidulated so that the final products contain about 50% of its total P in water-soluble form, are generally as effective as fully acidulated superphosphate. For permanent pastures the water P content may be reduced to about 40% of total P without reducing their agronomic effectiveness of the product. In medium P retentive soils pH seems to have little or no influence on the agronomic effectiveness of PAPRs. In highly P retentive soils increasing soil pH reduces the agronomic effectiveness of phosphoric PAPRs apparently by reducing the solubility of the PR component of PAPRs. Even at low pH the dissolution of unreacted PR in sulphuric PAPRs is less than that in phosphoric PAPRs, probably due to the possible coating of calcium sulphate on the residual PR in sulphuric PAPRs. Results on the agronomic effectiveness of PAPRs prepared from unreactive rocks were highly variable and no generalisation could be made regarding the degree of acidulation needed for the products to be consistently effective. Single superphosphate (SSP) cogranulated with reactive rocks (SSP/PR) was agronomically less effective than SSP, and also than phosphoric PAPRs of similar water-soluble P.     

Sintering of corundum ceramics based on aluminum hydroxide

The possibility of using aluminum hydroxide obtained by the precipitation method for synthesis of corundum ceramics with additives forming a liquid phase during firing and without additives, is investigated. The optimum parameters of the manufacturing process and the main properties of the material recommended for testing in the production of glass ceramic substrates for integrated circuits are investigated.     

Vibratory densification of thermal insulation corundum products

Conclusions During vibratory densification, the bulk density and the angle of repose of the corundum bodies based on hollow granules and a porous filler depend on the type of the filler used and the size of its grains. The relative settling and the relative density of the bodies obtained after densification are related to their bulk density and the angle of repose.We established the dependence of the shrinkage during firing, the apparent density, and the strength of the fired products on the bulk density, the degree of settling, and the relative density of the specimens after vibratory densification. At a given density, the products based on the corundum granules exhibit higher strength.We developed large-sized corundum products of complex shape for thermal insulation at 1800°C under reducing conditions.Translated from Ogneupory, No. 4, pp. 28–32, April, 1986.