Structural ceramic and fibrous materials based on quartz glass

Abstract

Ceramic and fibrous materials based on quartz glass with controlled porosity (0 to 90%) and technologies for fabrication of complex-shaped components developed at the Tekhnologiya Research and Production Enterprise are described. Properties of structural ceramic and heat-protecting fibrous radio transparent materials for use in aerospace and aircraft technologies are reported. Techniques for improving the strength of thin-walled ceramic shells operating under heavy-duty conditions are described.Development of aerospace technology has stimulated a search for ceramic materials that would combine high thermal stability, low heat conductivity, and constancy of dielectric properties over a wide range of temperatures and frequencies. The materials had to be resistant to optical, highfrequency and ionizing radiation and be operable in vacuum and in oxidizing and reducing media. These requirements were adequately met by materials based on amorphous silicon oxide (quartz glass) that could be prepared by a ceramic technology using powdered or fibrous raw products.Ceramic materials based on quartz glass are a relatively recent addition to the class of inorganic materials [1,2]. Studies that were conducted in the U.S.A. and the USSR in the late 1950s have led to a range of structural and heat-protecting materials differing in properties and manufacturing technologies. A conventional classification was proposed: vacuum-dense ceramics (open porosity P = 0), structural (P = 5 -15%) and porous (P = 20 -25%) ceramics, high-porosity heat-protecting materials (P = 60 -95%), unfired ceramics, SiO 2 -based modified materials, laminated ceramic composites, and ceramic castables.The increased interest in materials based on amorphous silicon oxides stems from three factors:1. The unique set of dielectric, thermophysical, and chemical properties; as regards parameters such as thermal stability, radio transparency over a wide range of temperatures and frequencies, and heat protecting properties, these materials have no analogs, which makes them unmatched in research and technology.2. Ease of fabricability, large reserves of raw materials in many countries over the world, and readily available, simple technological equipment. Practically any established method in ceramic engineering can be used to treat quartz ceramics; the low shrinkage at drying and sintering temperatures (0.5 -2.0%) makes it possible to fabricate large-size components without buckling and strain.3. These materials have much room left for further updating and modifying to obtain products with high reliability and tailored properties.By properly modifying the treatment of raw materials and semi-finished products, molding techniques, and drying regimes, a technology was developed for materials and components with porosity varying from 0 to 90% [3].Properties of ceramic and fibrous inorganic materials based on quartz glass are summarized in Table 1. For ceramic materials, the basic technology is aqueous slip casting in plaster molds followed by sintering, and for fibrous ma...

The Features of Deformation and Destruction of Porous Diatomitebased Ceramics

“…The results of this set of experiments are shown at the insert of Figure 5. The numerical E values agree with the known literature data on high-porous quartz ceramics (Pivinsky and Romashin, 1974;Lou and Stevents, 1999;Romashin et al, 2004).…”

“…The obtained results are presented in Figure 5. One can see that elastic modulus of the considered high-porous material is two orders of magnitude less than that of the crystalline one (Lou and Stevents, 1999;Romashin et al, 2004). Similar results were also obtained by measuring the dependence of dynamic elastic modulus on sample density.…”

Slip-Cast Fused Silica Radomes for Hypervelocity Vehicles: Advantages, Challenges, and Fabrication Techniques

“…The electrical properties of fiber-reinforced plastics (FRPs) listed in Table 4 are relatively good up to the temperatures indicated [3,[26][27][28]. The most widely employed resins for RF radome fabrication are polyester, epoxy, phenolic, and silicone.…”

“…However, this class of materials is experiencing steady development for uses up to this range Radomes that travel at a speed of Mach 3 are typically made of polymer matrix composites, such as, glass fiber/epoxy, quartz fiber/bismaleimide, quartz fiber/cyanate ester, glass fiber/polyimide, alumina-boria-silica fibers/polybenzimidazole, etc. [3,[26][27][28]. When radomes are used at high speeds (Mach 3 to Mach 5), their physical and mechanical properties have to be considered to withstand temperatures in the range of 500-800 C and for tougher environmental conditions [29].…”

Study of optical and cooperative parameters of fibrous quartz heat shielding on experimental data on its reflection spectra

“…The typical average diameters of fibers are also close to this range. In Russia, TZMK [1] silica fiber materials produced by ORPE Technologiya in Obninsk (TZMK-10 (99.8% SiO 2 ) and TZMK-10M (99% SiO 2 )) are commonly used. The degree of purity of amorphous quartz in them has a significant effect on both the spectral absorption coefficient and the cost of material production.…”