Solid Freeform Fabrication of Functional Silicon Nitride Ceramics by Laminated Object Manufacturing 1

The processing of silicon nitride (Si3N4) structural ceramics by Laminated Object Manufacturing (LOM) using ceramic tape preforms was investigated. The key processing stages involved green shape formation (which used the LOM process), followed by the burnout of all organics, and final densification by pressureless sintering. Two material systems were considered. These were a) monolithic Si3N4 and b) a preceramic polymer infiltrated Si3N4. The raw materials for the process were tape preforms of Si3N4, which were fabricated by standard tape casting techniques. Mechanical property data obtained for the LOM processed Si3N4 showed high strength and fracture toughness values. The room temperature and high temperature (1260 o C) flexural strengths were in the range of 700-900 MPa and 360-400 MPa, respectively. The fracture toughness averaged from 5.5-7.5 MPa.m1/2. These strength and fracture toughness values are comparable to those reported for conventionally prepared Si3N4 ceramics. Thus, this research demonstrated that the LOM technique is a viable method for preparing functional Si3N4 ceramics with good physical and mechanical properties.Mechanical Engineerin

Complexes of Ethylene-1,2-bis-diphenylarsine with Pt(II & IV), Pd(II) & Ru(III)

174-17

Pm(III), Eu(III), Tb(III), Pd(II), Pt(II) & Ir(II) Complexes of Picramic Acid

470-47

Anaesthetic implications of a parturient with antiphospholipid antibody syndrome

No Abstract

Contributions to the theory of generalised hypergeometric series

This thesis deals with various aspects of development in the field of both ordinary and basic hypergeometric functions. It comprises six chapters. The first chapter gives a brief survey of some of the recents developments in this field including the work done in the present thesis. The second chapter gives a systematic study of the transformations connected with the partial sums of generalised hypergeometric series, both ordinary and basic. The main theorem proved in the chapter gives the most general relation of its type. The third chapter is concerned with the development of the transformation theory of bilateral cognate trigonometrical series and generalises all the known results in that field. The fourth chapter gives the integral analogues of some of the transformations of basic series analogous to those for the ordinary series in Chapter VI of Bailey's Cambridge Tract. The fifth chapter deals with a systematic classification and study of two and three term relations between special kinds of well-poised series of the type and gives a new method, by integrals, of deducing these transformations easily. The last and the sixth chapter gives a number of identities involving basic analogues of Appell's hypergeometric functions of two variables and some associated functions.<p

Studies on the Geology and Beneficiation of Chandak Magne-site Deposit from Pithoragarh District, Uttar Pradesh

Stringent operating conditions in modern steel making furnaces demand high quality basic refractories based on magnesia. Source of good quality natural magnesite cont-ains considerable amounts of SiO2 and fluxing agents. Therefore, appropriate measures are to be taken to ensure the availablity of good quality magnesite. Measures for meeting the demand of quality magnesite are follows:- i) Upgrading of the presently available natural magnesite by various beneficiation techniques ; ii) Production of high quality magnesia from sea water

Filament Feed Materials for Fused Deposition Processing of Ceramics and Metals

Fused Deposition of Ceramics (FDC) and Metals (FDMet) are SFF techniques, based on commercial FDMTM technology, for fabrication of ceramic and metal components. The FD processes use feed material in the form of filaments which require certain phy~ical and mechanical properties. FDC and FDMet processes employ fila.n::ents formed from ?erannc ~r metal powders mixed with thermoplastic polymers. The thermoplastic polymers act as bmder dunng the FDC and FDMet processing in forming a green part. Development of green ceramic or metal fIlaments for FDC or FDMet processing involves three critical steps : selection of an appropriate binder chemistry, appropriate mixing procedures and fIlament fabrication techniques. This study describes the properties required for filaments for successful FD processing and the approach taken in the development of a series of binder which meets these requisite properties for a wide range of ceramics and metals. Appropriate mixing and filament forming techniques are also discussed.Mechanical Engineerin

Pathological studies of Glaeosporium psidii causing die-back of guavas

This article does not have an abstract