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An outline is presented of theoretical treatments of the connection between various physical properties of glasses and a simple model of the network structure of these glasses. The following properties are included: (1) thermal capacity; (2) thermal expansion, (3) elastic properties; (4) viscous flow; and (5) stress optical properties.

Results are reported in attempting to utilize the devitrification process for ferroelectric ceramics. Frits were made and bodies prepared from the frits ranging from 85 to 91% BaTiO3, the remainder being B2O3. BaTiO3 is the crystalline phase devitrified from the 91% BaTiO3 frit while and unknown crystalline phase results at lower BaTiO3 contents. Electrical data versus temperature and frequency are reported. The electrical properties of bodies produced by the devitrification of glass frits containing 91 parts of BaTiO3 and 9 parts of B2O3 plus small additions of the oxides of Fe, Ni and Sn are reported. Dielectric constants for these bodies are approximately 30 and dissipation factors about 0.019. The as-received strength of a random sample of 25 micromodule wafers (94-96% Al2O3) is reported. Thermal conditioning data are presented and evaluated. (Author)

The control of properties by structural means through substitution in the RO, R2O3 and RO2 groups of a complex crystalline phase such as beta-spodumene is investigated. Combinations of 3 alkalies additives to composition F-E(1) (55% SiO2 - 45% BPO4) were studied. Results (1 Mc) are reported for all compositions prepared as glasses and as bodies devitrified from the glasses. A preliminary study of boron nitride additions to composite F-E(1) is reported, the objective being to determine its effect of ultra low loss properties of this type composition. n attempt to prepare 100% boron nitride ceramics under normal firing environment is reported along with the general properties of this material. A loading mechanism for the micromodule strength testing apparatus is described. Preliminary data on as-received strength are reported and discussed. A study of the effect of small variations in particle size distribution and composition and the sinterability and densification of a high alumina body (92%) was undertaken. (Author)

Low loss microwave ceramic dielectrics on compounds were investigated in the ternary system La2O3-SiO2-Al2O3. In work on low loss boron nitride ceramic dielectrics bodies containing boron nitride and two undevitrifiable glasses were prepared and evaluated. Hot pressing and sintering were employed in an effort to produce dense translucent aluminum oxide bodies. Theoretical density was achieved by hot pressing but the specimens were contaminated with graphite from the mold used. Temperatures reached in gas firing were not high enough to produce maximum density. Results of thermal conditioning of micromodule wafers having BaTiO3 and TiO2 as their chief crystalline phase are reported. The effects of conditioning upon camber and electrical properties are discussed. The results obtained in the conditioning of wafers are compared with those obtained in the earlier work on rod-shaped specimens. Work on high temperature extrusion of barium titanate is in preliminary stages. A review of the progress made in this area is reported along with a resume of the work reported by Nuclear Metals, Inc. A 150 ton press has been ordered to continue this work. AD-287 1689N3 +++Properties of ceramic dielectric materials for possible use in microwave equipment; crystal formation and methods of preparation of glass containing these materials; mechanical and electrical properties.

A comparative study is reported on a boron phosphate silica type composition prepared as a glass, a devitrified body and hot pressed body. The electrical properties versus temperature and frequency indicate that this type composition approaches fused silica. Specimens of lanthanum aluminate were prepared by sintering and hot pressing. A dielectric constant of 25 was obtained for this material. The as-received strength of random samples of 10 types of micromodule wafers is reported. The two approaches to making barium titanate glass are the use of new glass formers and faster frit quenching methods in order to produce a good glass free of devitrified material. A calcium boro-aluminate frit was substituted as the glass former and the flame spraying of 100% BaTiO3 was tried both in an oxygen-hydrogen flame and an oxygenacetylene flame. A study was initiated to attempt to remove the glass forming oxide (B2O3) from the barium titanate-boric oxide frit. The object is to increase the barium titanate content in order to improve the dielectric properties of this type of ferroelectric.

Attempts were made to develop refractory ceramics for radomes that can be processed at temperatures considerably lower than their maximum use temperature. High alumina bodies containing 94 and 96% Al2O3, were developed with excellent engineering properties when matured in the range 2600 to 2800 F. The low maturing temperature and the excellent physical properties of these bodies were attributed to a presintering process. Studies were initiated on the mechanisms that enable a presintered body to mature at lower temperatures with superior physical properties. The incorporation of a devitrifiable glass in an alumina matrix and the total fritting of a refractory composition were also investigated. (Author)

Devitrified barium titanate ceramics on flame spraying barium titanate into distilled water, in order to make a glass, approximately 3.5% baria desolves in the water. This occurred with the several barium titanates investigated. Attempts to minimize or eliminate the solution of baria during this operation have failed. Ultra low loss ceramics: the system Lanthana-AluminaSilica was evaluated for ceramic bodies. Crystallinge ceramics research is discussed. Study of boron nitride and the effect of additives on its hygrosc6picity: the cause of the deterioration of electrical properties of hot pressed boron nitride is reported along with a procedure for making hot pressed boron nitride. A program for tying-up certain loss producing ions is discussed. (Author)