Prospects are discussed for the use of BeO-ceramic in electronic and other fields of technology and special instrument building. With use of BeO-ceramic in electronic technology one of the main parameters is its high thermal conductivity. Analysis of publications shows that BeO-ceramic in the range 300 -500 K exhibits the highest thermal conductivity among all ceramic materials used in electronic technology. Results are provided for a study of the thermal conductivity of 170 ceramic specimens made from BeO-ceramic with an identical configuration and dimensions prepared from one batch of BeO starting powder. It is established that the average size of microcrystals and the density of specimens have a defining effect on thermal conductivity.One of the most important properties of ceramic based on beryllium oxide is its high thermal conductivity: among other well-known oxide ceramic materials (Al 2 O 3 , MgO, SiO 2 , ZrO 2 , ThO 2 , etc.) BeO-ceramic has the highest thermal conductivity, by a factor of three than for ceramics based on MgO, and by a factor of 4 -6 or more, than for ceramics based on Al 2 O 3 [1]. The thermal conductivity of BeO-ceramic is 230 -330 W/(m × K) depending on its density, and it exceeds the thermal conductivity of beryllium metal and other metals with the exception of gold, silver and copper [1,2].Beryllium ceramics exhibit not only high thermal conductivity, but also a unique combination of other physicochemical properties such as high chemical, thermal, radiation resistance, a considerable specific volumetric resistance, low dielectric losses, transparency for vacuum, ultraviolet, visible, infrared, x-ray and ultrahigh frequency (UHF) radiation. This makes BeO-ceramic a promising material for use in contemporary electronics, new fields of technology and special instrument building [2], and in high-current UHF technology there is no alternative to BeO-ceramics.Currently objects made from BeO-ceramic are used extensively as:-refractory material in special metallurgy with melting of chemically corrosive substances, pure, ultrapure, expensive and refractory metals (beryllium, uranium, plutonium, iron, nickel, and molybdenum, and also high-purity gold, silver, platinum, lead, cobalt, silicon and titanium); -structural material in electronic technology making it possible to miniaturize electronic and electrical circuit components;-dielectric discharge channels of resonators, shells of active elements, hollow dielectric waveguides for waveguide gas lasers, and also optical quantum generators of a broad spectral range, i.e. from ultraviolet (UF) to infrared (IR) regions of the spectrum; -insulators and heat conductors, substrate-crystal holders of powerful UHF transistors and ultra-large integral circuits, microcircuits; -windows and insulators for high-current UHF technology, powerful on-board radars;-structural elements for travelling-wave lamps; -powerful heat transfer elements in cryogenic technology; -material for heat release of a matrix element in nuclear reactors;-neutron reflectors, neut...

The physicochemical and electrophysical properties of ceramics based on BeO without impregnation and after impregnation with an aqueous solution of sodium carbonate Na 2 CO 3 are studied. It is established that impregnation leads to preparation of ceramic specimens with a white color, which develop increased porosity, lower amount of impurities and smaller average microcrystal size, although it has little effect on their electrophysical properties. In order to improve these properties considerably it is necessary to increase ceramic density by increasing its sintering temperature by 20 -40 K. Values of electrical permittivity e and dielectric loss tangent tg d are determined for a series of BeO ceramic specimens (732 pieces), having identical geometric dimensions, but prepared from original BeO powder of different batches. Studies show considerable scatter in the distribution of these parameters, which points to a requirement for further improvement of BeO-ceramic preparation technology.One of the most important tasks is improving the quality of beryllium oxide ceramics, used in radio electronic devices and other areas of technology, and special instrument building. Previously the effect has been established for some impurities on the physicochemical properties of BeO-ceramic prepared by normal ceramic technology (methods of semidry compaction and slip casting), and high-temperature compaction [1 -10]. It has been established that introduction into the BeO-ceramic composition of an admixture of TiO 2 and sintering specimens in a reducing atmosphere made it possible to increase to a considerable extent their electrical conductivity and capacity for absorbing UHF-radiation [8 -10]. Impurity phases of iron have a defining effect on the change in electrophysical properties of BeO-ceramic, which limits its use in objects for electronic technology [1 -7].In order to reduce the unfavorable effect of primarily iron impurity and partly other admixtures on color, microstructure and electrophysical properties of BeO-ceramic objects, production operations have been proposed previously for impregnating porous ceramic preforms, after burning off the organic binder, in aqueous solutions of lithium carbonate Li 2 CO 3 [1, 6, 7]. As a result of this stabilization of microcrystal dimensions is achieved, coloring of the surface and volume of an object is suppressed, and there is also a reduction in values of dielectric permittivity e and dielectric loss tangent tg d. We have considered features of the impurity states of lithium and sodium in .The effect of impregnating BeO-ceramic in a solution of sodium carbonate on its properties has not been studied entirely. In view of this it is important to study the change in physicochemical properties of BeO-ceramic without impregnation and after it in aqueous sodium carbonate Na 2 CO 3 solution. In the present work comprehensive study is attempted for a number of most important functional properties of BeO-ceramic (mechanical strength, linear thermal expansion coefficient, volumetric elect...

An x-ray spectrographic method with an electron probe and a scanning electron microscope are used to study industrial ceramic specimen surface composition, distinguished by presence of a different color for both the main part, and impurity phases. BeO-ceramic specimens, having a visually differing color, are conditionally separated into three types. In reflected electron microphotographs impurities are distinguished qualitatively with respect to electrical conductivity. Iron impurity is invariably present within the composition of electrically conducting phases and inclusions. Apart from iron, all impurity phases contain carbon, aluminum, silicon, and calcium, and within individual phases there are admixtures of manganese, magnesium, chromium, potassium, sodium, zinc, phosphorus, and chlorine, which may be introduced into BeO-ceramic during production and sintering in repeatedly used industrial furnaces from linings and residual atmosphere.Keywords: BeO-ceramic, impurity phases, inclusions, microstructure, color of impurity phases in reflected electrons, specimens, electrically conducting phases, phase composition.Ceramics based on beryllium oxide due to its high thermal conductivity (reaching 330 W/(m·K)), thermal, chemical, and radiation resistance, high dielectric and strength properties, are used extensively in special metallurgy, nuclear, space, electron, and laser technology [1 -6]. It is a transparent material for vacuum ultraviolet, x-ray, and UHF radiation. Beryllium ceramic is a most promising material for quantum electronics, where it is used in powerful ion and molecular gas optical quantum generators as dielectric tubes of optical resonators and hollow dielectric waveguides in waveguide gas discharge lasers of the central IR-range (1,3,5]. Light-transmitting BeO-ceramic is considered as a new material for creating solid-state lasers in the ultraviolet region of the spectrum [7]. Recently BeO-ceramic has been used as a material for high-voltage insulators in chambers with magnetic compression in order to obtain high-temperature magnetized hydrogen plasma, within which there is thermonuclear reaction [1]. It is well known that impurity atoms have a considerable effect on electrical and physicochemical properties of beryllium oxide [8]. Impurities may change thermal conductivity, dielectric permittivity, and optical properties, and affect microstructure morphology, rate of BeO crystal growth, and ceramic operating properties. After modification with certain impurities BeO-ceramic may be used as effective scintillators, working bodies in thermoluminescent, exoemission, and electron paramagnetic resonance dosimeters of ionizing radiation [1].Impurities connected with beryllium oxide may be separated into several groups [1, 2]: -anionic, affecting object density during sintering (fluorides, sulphates, and phosphates); isomorphic substituting beryllium ions in a cation sub-lattice (Li + , B 3+ , Zn 2+ , Al 3+ ) or arranged predominantly in octahedral internodes of BeO (Na + ); -covering ceramic objects and...

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