Z. K. Zykova

Study of the thermal-shock resistance of ultralightweight refractories

ConclusionsA complex investigation was carried out into the thermal shock resistance of ultralightweight refractories ShUB-0.4, ShLB-0.6, and ShLBDS-0.4. Using calculations and experimental techniques and specimens in the form of plates and standard bricks we established the criterion values for thermal shock resistance. It was shown that the refractory ShLBDS-0.4 is the most thermally shock resistant product of those investigated.

Sonic method for checking the thermal shock resistance of steel-casting plugs

ConclusionsA method was developed for determining the thermal-shock resistance of steel casting plugs from the frequency of the mechanical oscillations using the sonic method without breaking the products.The sonic method of checking the properties of the plugs enables us to increase the working reliability of stopper devices during the casting of steel by means of a greater representation of the sample plugs, accelerating the certificating process by a factor of ten, and improving the working conditions.The method has been introduced for checking the properties of samples in enterprises of the refractories and metallurgical industry. The introduction of the method will give a substantial economic saving.

Method of determining the inherent oscillation frequency of steel-casting plugs

ConclusionsA method was developed and apparatus designed for determining the basic tone of the longitudinal oscillations and simultaneous checking of the nature of the deformations developing in steel-casting plugs.The method allows experimental studies to be made to establish the connection between the frequency of inherent oscillations in steel-casting plugs, and their porosity, and thermal-shock resistance. The results of these studies will be published subsequently.

Study of the strength of ultralightweight refractories

ConclusionsA design for equipment and a test method were developed for studying ultralightweight refractories. We obtained temperature relationships with the tensile, bending, and compressive strengths of refractories ShLB-0.4 and ShLB-0.6. A considerable increase in the strength of these refractories was noted at 900°C.

Study of the elastostrength properties of insulating refractories by the resonance method

ConclusionsBetween the elasticity modulus and the compressive strength of heat-insulating lightweight refractories there is a close correlation factor which is almost linear.Since the elasticity modulus determined (without breaking the products) by the resonance method gives a more objective idea of the strength properties of insulating products than the compressive strength (GOST 4071-69), in future this factor may be used for characterizing the strength of insulating refractories.The results of the study may be used for developing control methods for the spalling resistance of heat-insulating refractories [11–13].

Resonance method of measuring internal friction in refractory materials

ConclusionsA method was developed for determining the internal friction (attenuation coefficient) in refractory materials at room temperature, based on measuring the width of the resonance curve of forced oscillations. Information is obtained for the first time on the amplitude-independent attenuation coefficient of basic, aluminosilicate, and dinas refractories produced by industry.It can be assumed that the basic cause of the scatter of electric energy during cyclic deformation (about 103 cps) in polycrystalline material is the change in the temperature in individual microvolumes as a result of the heterogeneity of the stresses and the development of thermal irreversible currents. Some influence on the internal friction may be exerted by the microplastic deformation of the individual grains in the material.

Sonic method of checking quality of insulating refractories

ConclusionsThe sonic method of checking the quality of insulating refractories is being introduced at the Snigirev Refractories Plant. This method accelerates the certifying of the products 12–15 times, improves the reliability of the checking process, and also improves working conditions. The method can be used in factories manufacturing insulating refractories.

Statistical method for checking the density of silica

ConclusionsAs a result of our investigations for the first time we were able to develop a method for determining the density without breaking silica products, based on the use of correlation relationships between density and group I parameters, the permitted limits of which can be determined by the control chart method.The method developed was checked and introduced for the specification of silica at the Pervourals Factory. This method enables us to accelerate the specification by a factor of 10–12 times compared with a pycnometric method, and by seven times compared with the rapid method.

Development and use of the sonic method for controlling the quality of refractories

ConclusionsWith the use of the sonic method of control for certifying finished production the test time is speeded up by a factor of 8–10 [5]. This method permits us to obtain a considerable saving on account of preservation of the products and elimination of costs connected with laborious operations, and the preparation of large numbers of specimens for the test. The sonic method of control increases the quality of the specimens and more completely reflects the quantitative factors of the products being tested.For further improvements [3, 6, 7, 8], and extensive use of the sonic method of control of the quality of refractory goods, it is necessary to arrange series production of radiotechnical apparatus of the type IChMK and to train the necessary teams.

Dynamic method of determining the lateral deformation of refractories

ConclusionsWe designed apparatus and developed a dynamic method for determining the coefficient of lateral deformation (Poisson ratio for refractories and other materials. Determination of μ by the method developed takes 8–10 min, which is much more rapid- and also cheaper-than the well-known static method.The direct dynamic method was used to obtain the first data characterizing the coefficient of lateral deformation of magnesite, firebrick, silica, and magnesite-chromite refractories at room temperature.The studies show the complexity of the question of determining elastic constants of materials of heterogeneous structure, including refractories, and the need for multi-lateral experimental and theoretical work in this area.