Showing papers in "Transactions of The Indian Ceramic Society in 1978"
TL;DR: In this paper, the effect of particle size of Al2O3 and glass content were studied from isothermal density variation, and it was found that CAS(2) glass was more effective in promoting sintering of alumina than CAS (1).
Abstract: Sintering of alumina has been carried out in presence of two eutectic glass compositions, viz. CAS (1): CaO–23.0, Al2O3–15.0, SiO2–62.0 and CAS (2): CaO–52.0, Al2O3–41.5, SiO2–6.5. 10, 15, 20 and 25 per cent by weight glass were used with different particle sizes of Al2O3 and sintered at 1400° and 1460°C. Effect of particle size of Al2O3 and glass content were studied from isothermal density variation. It was found that CAS(2) glass was more effective in promoting sintering of Al2O3 than CAS (1).
7 citations
TL;DR: In this paper, a tri-component eutectic made from a mixture of magnesium oxide, aluminium oxide and silica was used for sintering of MgO and Al2O3.
Abstract: Investgetions were carried out on eutectic sintering of MgO and Al2O3 with a tri-component eutectic made from a mixture of magnesium oxide, aluminium oxide and silica. An intimate mixture of tri-component eutectic with 20.5% MgO, 17.5% Al2O3 and 62% SiO2 was prepared at 1400°C for 2 hours. The densification behaviour and microstructure have been studied on pellets of MgO and Al2O3 using 3, 5, and 10% by wt of the eutectic mixture at temperatures varying from 1350° to 1600°C. The study revealed that 3 and 5 wt % of the eutectic liquid was just sufficient to attain the approximate theoretical density of magnesia and alumina respectively. The shrinkage data ware analysed to understand the mechanism of sintering.
5 citations
TL;DR: Workability of various mixes with different water content has shown that workability increases from 1:1.0 to 1:2.0 and thereafter it decreases from 1.2.5 to 1.5 and 1:5.0.
Abstract: Workability of cement, lime and sand mortars was studied by the measurement of flow on a flow table. Effects of cement and sand proportions were investigated by taking various mixes from 1:1.0 to 1:5.0 cement: sand mortars. 1:2.5, 1:3.0 and 1:3.5 cement: sand mixes were further studied by the use of lime as workability aid.It was found that mixes of cement and sand from 1:1.0 to 1:4.0 ratio behave like plastic masses and workability increases by increase in water content without any yield point. 1:4.5 and 1:5.0 cement: sand mixes gave certain yield values. Overall workability of various mixes with different water content has shown that workability increases from 1:1.0 to 1:2.0 and thereafter it decreases from 1:2.5 to 1:5.0 cement: sand mixes. The effect of lime was that it increases the workability in each case and the effect is more marked at higher lime contents in the mixes.
5 citations
TL;DR: The results indicated the presence of illite (2: mical type) as the dominant clay mineral with traces of kaolinite in alluvial soil clays (pond sediments) as mentioned in this paper.
Abstract: The X-ray, DTGA and chemical analyses of clay fractions isolated from alluvial soil clays (pond sediments) were carried out. The results indicated the presence of illite (2: mical type) as the dominant clay mineral with traces of kaolinite. The X-ray basal spacings and the DTGA peak temperatures were observed to be lower than the standard samples (cf. fithian illite). The molar ratios of SiO2/Al2O3 were also found be lower. All these indicated the presence of minerals (cf. kaolinite) other than illite as the only constituent.
4 citations
TL;DR: In this article, the thermal properties of the alumina gel were studied by qualitative identification of phases and quantitative estimation of mullite formed, by X-ray, and then compared to that of kaolinitic clay.
Abstract: Alumina gel was prepared in presence of colloidal or amorphous hydrated silicic acid gel. The gel gives a first exothermic peak which is exactly similar to that of kaolinitic clay. Thermal characteristics of this gel were studied by qualitative identification of phases and quantitative estimation of mullite formed, by X-ray, and then compared to that of kaolinitic clay. It is found that the thermal change of the gel (of molar ratio SiO2: Al2O3 2:1) is quite analogous to that of kaolinite, and that mullite formation in both the cases follows the same course and same mechanisms.
4 citations
TL;DR: In this article, the influence of repeated calcination and grinding of mixtures calcined between 1200° and 1500°C and sintered at 1400° and1500°C for duration of ½ hr to 4 hrs was investigated, with a view to accelerating the formation of mullite phase.
Abstract: Attempts were made to study the relation between calcination treatments and formation of mullite in clay-alumina mixtures, with a view to developing mullite body compositions. The influence of repeated calcination and grinding of mixtures calcined between 1200° and 1500°C and sintered at 1400° and 1500°C for duration of ½ hr to 4 hrs was investigated, with a view to accelerating the formation of mullite phase. Minor addition of MgCO3 was made in some trials. Mixtures repeatedly calcined at 1500°C and ground, and sintered at the same temperature attained bulk densities over 95% T.D. With MgCO3 addition, densiflcation of the same order was obtained at a lower temperature of sintering (1400°C). Microstructural studies on thin sections of the sintered samples as well as X-ray diffraction studies revealed that batches with stoichiometric ratio of clay and alumina would need repeated calcination and sintering at 1500°C for the substantial formation of mullite phase; while with MgCO3 addition, larger proportion ...
2 citations
TL;DR: The effect of minor additions of barium oxide and titania on the formation of forsterite from pure raw materials and commercial grade raw materials was studied at 1450°C as discussed by the authors.
Abstract: The effect of minor additions of barium oxide and titania on the formation of forsterite from pure raw materials and commercial grade raw materials was studied at 1450°C. It was observed that Ti02 was more effective than BaO in the formation of forsterite phase. The addition of 2-3 wt% of each additive produced an optimum value of density and dielectric constant of the forsterite ceramics.
2 citations
TL;DR: In this article, the IR absorption spectra of four clay samples of Nepal are studied by KBr pellet technique and it was observed that Daman, Panchmane and Dalcap clay spectra show the two distinct peaks of a kaolinite in the OH absorption region.
Abstract: IR absorption spectra of four clay samples of Nepal are studied by KBr pellet technique. It was observed that Daman, Panchmane and Dalcap clay spectra show the two distinct peaks of a kaolinite in the OH absorption region. Daman clay spectrogram also shows some peaks between 910 and 1125 cm–1 which are assigned to a kaolinite mineral. On the basis of this study, it is, therefore, suggested that Daman clay is more kaolinitic than the Panchmane and Dalcap clays.
2 citations
TL;DR: In this paper, a counter current fluidized bed calciner was designed for heat activation of clays and a pilot plant of capacity of 2 tonnes per day was set up at the Sri Ram Institute for Industrial Research.
Abstract: Applying the principles of fluidization, a counter current fluidized bed calciner was designed for heat activation of clays and a pilot plant of capacity of 2 tonnes per day was set up at the Sri Ram Institute for Industrial Research. The pilot plant studies revealed that the fluidized bed technique could be effectively used for production of clay pozzolana. It has advantages such as high thermal efficiency, lower floor space, and it is economical compared to the conventional methods. Based on these studies, a demonstration-cum-production plant of capacity of 20 tonnes per day has been set up by National Buildings Organisation at Sultanpur, Delhi, where uniform quality of pozzolana conforming to IS specifications is being produced.
2 citations
TL;DR: In this paper, the application of infrared spectroscopy as a follow-up of the process of cement manufacture has been demonstrated with the help of IR characterization of kiln feed and clinker samples obtained from a vertical shaft kiln plant as well as of ring samples collected from a rotary kiln.
Abstract: The application of infrared spectroscopy as a follow-up of the process of cement manufacture has been demonstrated with the help of infrared spectroscopic characterization of kiln feed and clinker samples obtained from a vertical shaft kiln plant as well as of ring samples collected from a rotary kiln. The possibility of employing the infrared spectroscopic technique for a broad quality control of ordinary portland cement and clinker has also been highlighted.
2 citations
TL;DR: In this paper, China clay-alumina mixtures were sintered at 1400°-1600°C for 2-12 hours and four different sources of alumina and a variety of mineralisers were evaluated.
Abstract: China clay-alumina mixtures were sintered at 1400°- 1600°C for 2–12 hrs. Four different sources of alumina and a variety of mineralisers were evaluated. Mullitization from 40 to 100 per cent takes place, depending upon the fineness of alumina, clay/alumina ratio, sintering temperature, and time and mineralisers. Finer alumina and a clay/alumina ratio of 57/43 are preferable. Transition metal oxides were generally more effective and the optimum amount was about 1 per cent. Porosity of the sintered products varied between 4 and 40 per cent.
TL;DR: The effect of tetravalent, divalent and monovalent additives on the physical properties of steatite bodies were studied at various temperatures (1300°-1400°C) as mentioned in this paper.
Abstract: The effect of tetravalent, divalent and monovalent additives on the physical properties of steatite bodies were studied at various temperatures (1300°–1400°C). Excellent electrical properties were exhibited by steatite compacts containing 1.5% ZrO2 and TiO2 at 1400°C.
TL;DR: In this paper, the effects of varying forming pressure, firing temperature and type of bond on the fired properties of Rajhauan (UP) bauxite are reported, and the porosity and water absorption were found to decrease with increasing forming pressure and firing temperature.
Abstract: The effects of varying forming pressure, firing temperature and type of bond on the fired properties of Rajhauan (UP) bauxite are reported. The porosity and water absorption were found to decrease with increasing forming pressure and firing temperature. Bulk density was found to increase with increasing forming pressure and firing temperature. The firing shrinkage increased with increasing firing temperature and decreased with decreasing forming pressure. The PCE and RUL values were reasonably good. It was concluded that the material could be used for making refractories.
TL;DR: In this article, high viscous mono-aluminium phosphate and aluminium-chromium phosphate were prepared from out of standard chemicals for the purpose of studying the relative advantages when employed for bonding inert aggregates of fused alumina.
Abstract: Highly viscous mono-aluminium phosphate and aluminium- chromium phosphate were prepared from out of standard chemicals for the purpose of studying the relative advantages when employed for bonding inert aggregates of fused alumina.These were incorporated in a mix composed essentially of fused grains of bauxite, constituting the relatively inert matrix with a view to developing some suitable ramming masses which might meet the severe conditions of applications at high temperatures. The cold crushing strengths of such bodies and also hot mechanical strength, as determined from refractoriness under load, and compressional torsional creep measurements revealed that aluminium chromium phosphate was superior to mono-aluminium phosphate in spite of its lower P2Os content. The enhancement of strength is ascribed to greater thermal stability of aluminium-chromium phosphate. © 1978, Taylor & Francis Group, LLC.
TL;DR: In this paper, the authors describe the growth and development of the Khurja Pottery Industry and its growth in the 1970s and 1980s, and present a survey of the industry.
Abstract: (1978). Khurja Pottery Industry—Its Growth and Development. Transactions of the Indian Ceramic Society: Vol. 37, No. 5, pp. 208-214.
TL;DR: In this paper, a solid solution of uranium-plutonium carbide with less than 0.1% oxygen content was prepared by carbothermic reduction of mixed oxides UO2 and PuO2 at 1700°C for 3 hours in vacuum.
Abstract: A solid solution of uranium-plutonium carbide with less than 0.1% oxygen content was prepared by carbothermic reduction of mixed oxides UO2 and PuO2 at 1700°C for 3 hours in vacuum. The carbides reduced in argon had higher oxygen content than those prepared in vacuum. It was found that the amount of sesquicarbide formed remained the same for carbon contents varying from 42.7 to 56.5 atomic% in vacuum reductions. However, single phase (U, Pu)C could be obtained with 47 atomic% carbon at 1700°C, and with stoichiometric amount of carbon at 1800°C. The lattice parameter varied from 4.9546A to 4.9657A depending on the conditions of reduction and composition. The plutonium loss during reduction was around 0.6%, while it was higher for the composition with 42.7 atomic% carbon. The pellets made from oxide reduced and arc melted carbide powders (<44 micron size) were sintered to 80–83% theoretical density at 1750°C. The same degree of densification could be attained at 1500°C with 5–10 micron size powders.
TL;DR: In this paper, the electrical properties of some laboratory-prepared ceramic insulants have been determined, utilizing some Jammu clays, both in their washed and unwashed state, and corresponding changes in physical properties like density and porosity are measured as a function of soaking period.
Abstract: Electrical properties of some laboratory-prepared ceramic insulants have been determined, utilizing some Jammu clays, both in their washed and unwashed state. Also, the corresponding changes in physical properties like density and porosity are measured as a function of soaking period.The electrical properties of insulants appear to be strongly dependent on the chemical and mineralogical composition of clays used, as well as the soaking periods employed. While the presence of titania increases the conductivity more strongly than iron oxide, it decreases the dielectric strength. The electrical response of insulants is fairly compatible with their porosity and densification data.
TL;DR: In this paper, the de Guzman and Dunn equation has been used to determine the viscosity of PbO-Bi2O3, Pb O-PbMoO4 and NaCl-RbCl system over 100°C temperature range.
Abstract: Viscosity has been determined for the PbO-Bi2O3, PbO-PbMoO4 and NaCl-RbCl system over 100°C temperature range, starting about 50°–100°C above freezing point of corresponding mixtures. All the measurements have been carried out under inert gas (argon) atmosphere. Viscosity has been found to vary exponentially with temperature for all the melts thus conforming to de Guzman and Dunn equation. Least squares programme have been used to And most suitable exponential equations for all the melts. Log η has been found to vary linearly with inverse of temperature for NaCl-RbCl system. Deviation from linearity of such plot for other two fused salt systems has been attributed to ionic association or complexation in molten state.
TL;DR: In this paper, the effect of Fe, Cu and S impurity ions on the electrical conductivity of antimony doped tin oxide films has been studied and the variation in conductivity as a function of film thickness due to the presence of these impurities has been investigated.
Abstract: The effect of Fe, Cu and S impurity ions on the electrical conductivity of antimony doped tin oxide films has been studied. The variation in conductivity as a function of film thickness due to the presence of these impurities has been investigated.
TL;DR: In this article, it was shown that when the powders were calcined in the temperature range of 800°-900°C, compacts having more than 95% of theoretical density with zero open porosity could be prepared by sintering at 1200°C.
Abstract: Polycrystalline barium titanate capacitors derived from the mechanical mixture of BaCO3 and TiO2 showed changes in the molar ratio between BaO and TiO2, phases other than tetragonal BaTiO3, lack of homogeneity, etc. The extent of such variations depends on the fabrication technology and these undesirable changes were ignored while studying the end properties. Hence, in the pesent study, highly pure (>99.9% pure), homogeneous and stoichiometric barium titanate was prepared by thermal decomposition of barium titanyl oxalate tetrahydrate. The ‘activity’ required for subsequent sintering of the compacts was suitably varied by calcination temperature in the range of 600°–1100°C. It was seen that when the powders were calcined in the temperature range of 800°–900°C, compacts having more than 95% of theoretical density with zero open porosity could be prepared by sintering at 1200°C. For the powders calcined at 600°–700°C or 1000°–1100°C, compacts with these physical properties were not obtained at such a low te...
TL;DR: In this paper, the relationship between physical property-composition diagram and temperature composition diagram for LiCl-KCl and Mo03-Na2MoO4 systems has been studied.
Abstract: Correlations between physical property-composition diagram and temperature-composition diagram for LiCl-KCl and Mo03-Na2MoO4 systems have been studied. Remarkable similarity between these two diagrams has been noticed for the first system. A conductance curve, 100°C above melting point, has been predicted from phase diagram for the second system, and arguments have been put forward to explain such variation of conductance with composition from reactions in molten state. Specific volume of the melts of the halide system have been expressed in terms of power series equations. © 1978, Taylor & Francis Group, LLC.
TL;DR: Magnesite, chrome-magnesite and magnesite-chrome bricks from all leading indigenous manufacturers and Indian steel plants were collected as discussed by the authors and the chemical composition, mineralogical condition have been analyzed.
Abstract: Magnesite, chrome-magnesite and magnesite-chrome bricks from all leading indigenous manufacturers and Indian steel plants were collected. The chemical composition, mineralogical condition have been...
TL;DR: A survey of the alternate binder materials has been made in this article and their impact on the ceramic fabrications of the modern day is discussed. Mechanism causing setting and strength development in the binders is briefly elucidated.
Abstract: Plastic clay has been a natural binder material for ceramic manufacture from the beginning of making pottery and it continues to find extensive usage even to-date. The conventional clay binder, however, is found to be inadequate in various fields of application, particularly when material other than clay is used for ceramic fabrications.A survey of the alternate binder materials has been made in this paper and their impact on the ceramic fabrications of the modern day is discussed. Mechanism causing setting and strength development in the binders is briefly elucidated.
TL;DR: In this article, the sintering behavior of UO2 powders prepared by decomposition of ADU depends on the calcination temperature and activation energy of the powders, and it was suggested that the powder can be exposed to high temperature for a very short time; whereby the surface becomes relatively inactive, leaving a major part of the activity within the powder.
Abstract: It has been established that sintering behaviour of UO2 powders prepared by decomposition of ADU depend on the calcination temperature. Powders heated close to the decomposition temperature have a low optimum sintering temperature and a low activation energy of sintering. However, these powders are pyrophoric, have a high surface area and do not have good flow and packing characteristics. To enable the retention of adequate sinterability and at the same time improve the powder characteristics, it was suggested that the powders can be exposed to high temperature for a very short time; whereby the surface becomes relatively inactive, leaving a major part of the activity within the powder. It was found that such powders have desirable physical properties and at the same time retain adequate sinterability.The powders were prepared by decomposition of ADU calcined at 500°C, flash heated to 900°–1400°C and sintered between 1200°–1600°C. The activation energy of these powders estimated by conventional method whi...
TL;DR: In this article, the feasibility of determining reproducible results on abrasion resistance of refractories was investigated with a view to ascertaining the feasibility for determining reproducibility results.
Abstract: The investigation was undertaken with a view to ascertaining the feasibility of determining reproducible results on abrasion resistance of refractories. Attempts for designing standard instrument are, so far, based on the relatively simple method of impingement of abrasive grain on the test specimen. Numerous variables associated with this method render it difficult to obtain accurate data. However, in consideration of the relative advantage of fabrication, and the ease of conducting experiments, one such apparatus was installed at CGCRI essentially as per BS method. Keeping other variables, e.g. type of abrasive, rate of abrasive-feed and air velocity constant, impingement with abrasives of relatively finer fractions provided an improvement of reproducibility in terms of material loss. The samples included in this investigation comprise aluminosilicate, silica, basic and carbon bricks. An attempt was made towards correlating abrasive resistance with such properties as porosity, bulk density, cold crushing strength, tensile strength, modulus of rupture and modulus of elasticity in addition to textural aspects. © 1978, Taylor & Francis Group, LLC.
TL;DR: In this paper, different types of structural defects of common occurrence in clay minerals have been discussed and various X-ray techniques for evaluating them from the observed diffraction patterns have been reviewed.
Abstract: Different types of structural defects of common occurrence in clay minerals have been discussed. The X-ray method of identification of these defects and the various X-ray techniques for evaluating them from the observed diffraction patterns have been reviewed.