مواد ایمپلنت سرامیکی Ceramic Implant Materials

Ceramic Implant Materials

مواد ایمپلنت سرامیکی

ABSTRACT

Ceramics are refractory, polycrystalline compounds, usually inorganic, including silicates, metallic oxides, carbides, and various refractory hydrides, sulfides, and selenides. Oxides such as Al2O3, MgO, SiO2, etc. contain metallic and nonmetallic elements. Ionic salts (NaCl, CsCl, ZnS, etc.) can form polycrystalline aggregates, but soluble salts are not suitable for structural biomaterials. Diamond and carbonaceous structures like graphite and pyrolized carbons are  covalently bonded. The important factors influencing the structure and property relationship of  the ceramic materials are radius ratios (§2.2.2) and the relative electronegativity between posi- tive and negative ions. 

 

شوک حرارتی دیرگدازها Thermal shock of refractories

Thermal shock  of  refractories 

شوک حرارتی دیرگدازها 

ABSTRACT

Being brittle and having low thermal conductivity, refractories suffer damage and sometimes fail in service as a result of thermal shock. While the approach of those making fine-grained technical ceramics is to make their products sufficiently strong to withstand thermal stresses the refractory technologist is more cunning. He uses, often little known, devices to provide resistance to thermal shock that minimise but do not eliminate damage to the component. In this paper the basic equations of thermal conduction and elasticity are presented and followed by some immediate results that should guide the designer of components subject to severe thermal environments. The influence of size and shape of the refractory components is then discussed along with ways in which refractory producers can engineer the thermal and mechanical properties. In particular, the methods used to tailor fracture behavior to optimize the thermal shock resistance are treated in some detail.

 

چگونه دیرگداز ریختنی مولایتی بسازیم؟!

Let's Make a Mullite Matrix!

چگونه دیرگداز ریختنی مولایتی بسازیم؟!

ABSTRACT

 In the paper "Let's make a castable!"1 we went tbrough proportioning of refractmy castables, and  the beneficial effect microsilica addition has on casting properties. It is however, not only flow and packing that are influenced by microsilica additions, also  high-temperature properties like hot-strength are affected. In the following paper, arguments are  put forward why microsilica additions at relatively high levels bring out the best of the  alumina-silicate castable. Implicitly this also shows why substitution of microsilica by reactive alumina may not be such a good idea after all.

میکروسیلیس ماده اولیه دیرگداز

MICROSILICA A versatile Refractory Raw Material

میکروسیلیس ماده اولیه دیرگداز؛ کاملاً انعطافپذیر و پرکاربرد

ABSTRACT

An overview is given on the applications of microsilica in refractories starting more than 40 years ago . The role of microsilica in binder systems for briks and castables are discussed including reaction mechanisms at various temperatures . Critical parameters in these reactions are pointed out . Examples of application in castables are presented.