THERMAL EXPANSION OF SILICA BRICK AND MORTARS1

Thermal expansion from 20 to 950°C and physical data of silica brick from various producing districts in the United States and Europe are presented. The variations in thermal expansion of brick from various parts of kilns are given for plants in the United States. The magnitude of variation of the thermal expansion of silica brick is quite small, the expansion ranging between 1.15% and 1.30% at the highest point of expansion. The expansion of the silica mortars varied between 1.30 to 1.52% depending upon variations in clay, quartzite, and bats. The variations in thermal expansion of silica mortars from various producing plants are also shown. Data on the effect of size of grain, clay content, and P.C.E. on the thermal expansion of mortars are given. An extensive bibliography on thermal expansion of silica brick appears with the paper.     

7.63m焦炉主要耐火材料简评

介绍了7.63m焦炉主要耐火材料的品种、数量、材质及各种砖型的验收技术条件,同时还对半硅砖、硅线石砖、硅火泥、格子砖等的应用问题进行了深入的讨论.7.63m焦炉炉体密封性好,但异型砖多,有些砖的成品率极低,复杂的炉体结构对焦炉生产操作和寿命是否有影响还需进一步的实践验证.     

A Discussion on Stability of Mg-Al-spinel Crown of Glass Melters

In order to understand the failure mechanism of magnesia-alumina spinel crown of glass melters,a discussion on the stability of Mg-Al-spinel crown of glass melters was given in this paper.The discussion focused on the weight balance in the crown arch made of spinel or silica bricks,the creep of spinel crown bricks at high temperatures,the thermal stress distribution in crown bricks as well as at brick joints,and the displacement behavior of crown arch during heat-up of glass melter.It is believed that the tangential stress in spinel crown is much higher than that in silica crown due to the large differenee in their densities,and that the thermal stresses in the crown brick result in opening of a part of the brickto-brick joints at the cold side of the crown,and increase of the tangential stress needed for balancing the weight of the crown.Both defect migration in lattice or along grain boundary and viscous flow in glass phase at grain boundary contribute to the creep of crown bricks at high temperatures.The creep of the matrix of spinel brick is more significant than that of coarse grains because impurities,such as silica and calcia,are concentrated in it.For keeping the crown stable during heat-up period it is important to adjust properly the horizontal positions of each skew brick as temperature increasing based on correctly evaluating the thermal expansion according to the thermal expansion coefficient of the crown brick.     

HIGH TEMPERATURE LOAD AND FUSION TESTS OF FIRE BRICK FROM THE PACIFIC NORTHWEST IN COMPARISON WITH OTHER WELL-KNOWN FIRE BRICK1

Seventeen samples of fire-clay brick from the Pacific Northwest have been tested with twenty-seven other commercial brands of fire clay, silica, magnesia, chromite, zirconia, diaspore, silicon carbide and crystalline alumina, as well as china clay and crystalline sillimanite products made at the University of Washington. The tests show that the fire-clay brick of the Pacific Northwest vary considerably in quality. According to the high temperature load test, the majority of the local brick are among the upper grades, some are to be classed with the best fire-clay brick and one equal to the best diaspore brick. The brick tested is not the best which can be made from Pacific Northwest materials, for the kaolins in eastern Washington and northwestern Idaho give opportunity for the production of an all-kaolin fire brick. A method is suggested for testing super-refractory materials under load at high temperatures similar to the standard load test for fire clay and silica brick except that the temperatures are measured by cones, and are raised until 10% linear deformation of the brick is obtained. The rate of heating and soaking varies with the brick under test, and the principles learned from the cone fusion test are used in the application of heat. A numerical value, expressing the area under the cone-shrinkage curve, affords an easy method for comparing the high temperature load resistance of various refractories. The brick which are best able to resist deformation at high temperatures are composed of crystalline materials which have developed a recrystallized bond of the same composition. These are crystalline silica, silicon carbide, corundum and sillimanite, and they resist deformation at temperatures close to their melting points. Amorphous materials like fire clay, diaspore, bauxite or even the very refractory crystalline materials lie chromite and periclase, which depend on amorphous silicates for a bond or are contaminated with silicate impurities. will fail with the softening of the bond of the amorphous impurities. The cone fusion of the brick as a whole can not be depended upon to indicate the resistance to load at high temperatures.     

焦炉炭化室硅砖样品的分析研究

在对使用了40多年的焦炉炭化室炉墙实施热修时拆下的一块硅砖样品进行了试验研究。研究表明:炭化室炉墙上的硅砖在使用40多年后,主体结构依然致密均匀,强度没有降低。硅砖在使用过程中,煤中的碳组分会渗入到砖的气孔中使砖成为所谓的"硅碳砖",碳的含量约为5%,这对硅砖和炼焦传热效率的提高都是有利的。煤中的灰分对砖的炭化面会造成熔蚀,但这种熔蚀非常缓慢,且渗透力差,不能成为硅砖损坏的原因。     

CHECKER BRICK FOR RESISTING ALKALINE SLAGS1

Checker brick of varying composition were tested by placing them in the regenerators of two glass tank furnaces. The operation of one furnace was representative of those making the usual grade of bottle glass while the other was operated at a considerably higher temperature and with a more corrosive dust. The amount of corrosion of the checker brick varied directly with the silica content of the brick. Those highest in alumina gave excellent service in the regenerator operating at the lower temperature. In the other regenerator, however, the. dust adhered to the high alumina brick and tended to clog the regenerator while it apparently fluxed and drained off of those higher in silica, leaving free passage for the gases. The brick were tested in the laboratory by making into cones with various percentages of the corrosive dust and determining the fusion point of the cones. The results agree closely with those obtained from the service tests. Detailed results including partial analyses of the brick and flue dust are given.     

THE FIRE BRICK MATERIALS OF PENNSYLVANIA1

Pennsylvania produces over 40% of all clay fire brick and over 70% of all silica fire brick made in the United States. In 1920 Pennsylvania produced and sold fire clay worth nearly two million, fire clay brick worth nearly twenty-two million, and silica brick worth over ten and one-half million, a total of thirty-four and one-half million dollars worth of brick and clay. Three kinds of material are used for the manufacture of this fire brick. (1) Soft fire clay from one horizon northwest of Pittsburgh and from the “main clay” of the Pittsburgh bed south of Pittsburgh. (2) Hard or flint clay which occurs in many counties of the State. The hard clays are described as occurring at a limited number of horizons in the Allegheny formation or “Lower Productive Coal Measures,” as being irregular in thickness and distribution, ranging from a feather-edge to fifteen or twenty feet in thickness and being of two types, “block” clay in which the structure is homogeneous, and “nodular” clay in which the structure is gnarly or knotty. Brief reference is made to the principal flint clay deposits of the State. (3) The third source of material for fire brick is ganister rock, a pure white quartzite occurring as a massive bedded sandstone at the base of the Silurian series and exposed abundantly in the zig-zag ridges across the central part of the State and as a similar white quartzite at the base of the Cambrian in the southeastern part of the State. A series of tests of flint clays and of soft clays used to mix with the flint clays is appended. These are derived mainly from Clearfield County which is the leading flint clay county.     

中国硅砖的生产与出口情况

近几年中国硅砖的内在质量和外观质量都有了显著提高 ,已达到或接近世界先进水平。中国硅砖年产量超过30万t,占世界产量的 70 %以上 ,并大量出口到日本、美国、加拿大等国家与地区 ;中国硅砖生产厂家与国外厂家的技术、贸易合作发展良好。加入WTO后 ,应进一步扩大与世界各国的科技合作和经贸合作 ,进一步提高和稳定我国硅砖产品的质量。     

THE CHANGES WHICH TAKE PLACE IN SILICA BRICK DURING THEIR USE IN OPEN-HEARTH FURNACES1

A test on silica brick during their use in open-hearth furnaces is described. Four zones of varying characteristics in a silica brick are noted. A table presents the changes composition and refractoriness which take place in brick used in basic and acid open-hearth furnaces. With highly converted brick, durability may be promoted indirectly greater structural stability of the roof.     

THE INSULATION OF ROOFS OF GLASS FURNACES

It is unjustifiable to assume that a furnace roof cannot be safely insulated. The principal variables controlling the possibility of safe insulation are: (1) temperature of bath below melting point of silica brick roof; (2) transparency of the atmosphere within the furnace, i.e., no possibility of impingement of dense hot flames. The data of this paper are taken from observations on a glass tank furnace in which the combustion rate (B.t.u. per cu. ft. per hr.) is very low. A testing method is described which will show whether or not insulation is safe for any given furnace, considering only the temperature of the inside face of the brick as affected by the application of insulation. The possibility that if the roof is insulated the progress of fluxing of the silica brick by dust and fumes within the furnace may be accelerated because the higher mean temperature of the brick is considered. In the furnace observed, corrosive dust and fumes were in the gases to a considerable extent, yet no unusual deterioration of the roof brick was noted after three years of insulation under continuous operation.     

选用优质硅砖,确保焦炉低耗长寿

介绍了各时期焦炉硅砖质量指标，重点讨论了硅砖质量对焦炉年伸长量，湿煤耗热量等各项指标的影响，担子同确保焦炉硅砖质量的具体措施和建议。     

Evaluation of the morphology and pore characteristics of silica refractory using X-ray computed tomography

Silica refractory has excellent high-temperature performance, but its apparent porosity is relatively high. In this work, samples obtained before and after creep testing of silica brick (1550 °C, 50 h), from used silica checker brick (existing only tridymite and amorphous) and from used dome brick (existing only cristobalite and amorphous) were investigated using a three-dimensional structure model based on X-ray computed tomography (CT). The results show that the porosity of silica brick was high but consisted mainly of interconnected pores, with a very small proportion of closed pores (smaller after long-term use). During the use of silica brick, the morphology and phase transformation caused large particles to rupture, and the mineralizer became liquid at high temperature. The broken particles and interconnected pores provided channels for the migration of the liquid in the brick at high temperature. The silica brick presented a homogeneous ceramic structure during long-term operation. Tridymite or cristobalite presented a solid frame leading to an excellent creep performance of the silica brick (the creep rate of the checker brick was ?0.16% at 1550 °C for 50 h). Results were discussed, compared with literature and a model for the transformation of the silica brick from a refractory structure to a homogeneous ceramic structure was established in this paper.     

PROPERTIES OF SILICA BRICK MANUFACTURED FROM SHARON CONGLOMERATE1

New developments in the field of silicate refractories include greatly improved refractoriness and a high development of desirable qualities in silica refractories manufactured from Sharon conglomerate. The nature of silica refractories in general is discussed and a résumé of materials utilized in the manufacture of silica brick in the United States is given. Several illustrations of this new refractory are included, as well as test data.     

MOTTLED OR COLORED SILICA BRICK*

Abstract During the burning of silica refractories, spots or areas of dark cream to a reddish-brown color may develop in some of the brick or shapes. This is often called mottling, and its occurrence during the manufacture of the product cannot be definitely controlled. Questions occasionally arise as to whether the colored brick are of as good quality as the uniformly cream-colored brick. No records are available to show or indicate that color as such has been a cause of shorter life or failure in service. Data are presented that were obtained from testing the mottled and light-colored brick, and these show that there is no practical difference between them; consequently, color alone should not be a criterion for judging quality. The traces of iron present in the silica used are a necessary constituent in the formation of the color. The light-colored product, however, contains the same quantity of iron. It is not entirely clear as to how the iron is present in the two types. Unknown conditions during manufacture are such that the traces of iron may be influenced to form either the light or mottled brick, but the process cannot be controlled. A considerable amount of experimental work is presented which shows the nature of the color behavior with comments on certain conditions that cause the color formation.     

ADAPTATION OF TUNNEL AND CAR KILNS TO FIRING REFRACTORIES1

The success of tunnel kilns in a given industry is largely determined by the choice of the type best suited to the requirements of that industry. This paper discusses the adaptation of the various types of tunnel kilns to firing glass house refractories, clay, fire brick and silica brick.     

Periclase-forsterite refractories from silica magnesite

Conclusions Periclase-forsterite refractories from silica magnesite of Beloretsk deposits are endowed with excellent properties.The density of periclase-forsterite brick is subject to a wide range of changes depending on the grain distribution of the mixture, molding pressure, sintering temperatures and the introduction of additives. The effect of additives on the sintering of periclase-forsterite mixtures from silica magnesite has the same pattern as in the sintering of pure magnesium or regular magnesite. The most effective sintering additives are titanium and zirconium dioxides. Additions of ZrO₂ produces a higher refractoriness-under-load of periclase-forsterite brick.Periclase-forsterite brick is highly-resistant in regenerator checkers of open-hearth furnaces. This is caused by peculiar changes in its mineralogical structure which occur during service, i.e. recrystallization of periclase in top layers which brings about higher density instead of looseness as in forsterite refractories bonded with unite.The forming and the properties of periclase-forsterite refractories as they depend on such factors as basic raw material, manufacturing methods and phase composition need further studies and large-scale testing in order to determine the rational areas of application.     

202.5m硅砖隧道窑技术改造

针对 2 0 2 .5m硅砖隧道窑存在的主要问题 ,提出了切实可行的技术改造方案。该方案实施后 ,其主要技术经济指标显著提高     

梅钢焦炉用后硅砖显微结构分析

显微结构分析表明:焦炉炭化室用后硅砖中或多或少存在残余石英,而燃烧室由于温度较高,其硅砖中的石英逐渐经亚稳方石英转变为鳞石英.焦炉用后硅砖的相变过程只限于石英和亚稳方石英的转化,随着石英和亚稳方石英逐渐转变成鳞石英,硅砖结构趋于稳定.炭化室用后硅砖表面出现碳沉积并石墨化,对硅砖起到保护作用,并有利于提高炭化室的热导率.     

THE HEAT BALANCE OF A GLASS TANK FURNACE1

A seventy-two hour test was carried out on a continuous side-fired regenerative glass tank furnace with five oil burners on each side. A novel feature of this furnace was the insulation of the entire silica brick cap by means of a high temperature insulating brick. A complete record of the furnace operation during this period is given. Temperature measurements were made a t various points in the furnace and regenerator. A feature of the temperature observations is the great magnitude of the radiation correction when hot gases are flowing through passages lined with cooler brick work. The method described by Kreisinger and Barkley was used in making these measurements. This method could be employed for direct reading of true temperature at any point in the regenerative system. The heat balance of the complete furnace system between points at bottom of regenerators is given. Possible savings of fuel amounting to 14% of the total fuel burned are shown. An important fact brought out by this heat balance is that leakage through furnace brickwork is as prolific a source of heat loss as flow of heat through them by conduction.     

玻璃窑用优质硅砖的相变及损毁机理

分析了残砖各段带的化学成分变化及相组成变化 ,指出硅砖的损毁机理是相变和蚀损。高纯致密的优质硅砖可以提高玻璃窑的使用效率和使用寿命