Preparation of Ultra Fine Grained Magnesia Ceramics and the Temperature and Porosity Dependence of Their Fracture Behaviour
نویسندگان
چکیده
Fine grain polycrystals of MgO have been prepared from a Mg(OH)2 powder by reactive hot-pressing at 900°C. The densification rate is discussed in terms of superplastic deformation. The bend strength and the effective surface energy for fracture initiation y. have been determined as a function of porosity between room temperature and112000~. A rapid increase in yi with temperature is observed above 800°C. This behaviour is related to the observation of a superplastic deformation in these temperature and grain size ranges.
منابع مشابه
Effect of Silicon Carbide and graphite additives on the pressureless Sintering mechanism and microstructural characteristics of Ultra-High Temperature ZrB2 Ceramics Composites
The effect of SiC content, additives, and process parameters on densification and microstructural properties of pressureless sintered ZrB2– (1–10 wt %) SiC particulate composites have been studied. The ZrB2–SiC composite powders mixed by Spex mixer with 1-2wt% C (added as graphite powder) and CMC have been cold-compacted and sintered in argon environment in the temperature range of 1800–2100ºC ...
متن کاملEffect of Adding Nanoclay on the Mechanical Behaviour of Fine-grained Soil Reinforced with Polypropylene Fibers
In this study the performance of clay nano-particles on the soil reinforced with Polypropylene fibers (PP-fiber) has been investigated. Also a series of investigations concerning the effect of random orientation of fibers on the engineering behaviour of soil were conducted. Soil mixtures were modified with varying percentages of nanoclay and Fibers. Unconfined compressive strength (UCS), Compac...
متن کاملStudy on the strengthening mechanisms and failure modes of the ultra-fine grained tri-modal Al5083-5wt. %B4C-Al2024 and Al5083-5 wt. %B4C-Al5083 composites
In this paper, the influence of Al2024 and Al5083 aluminum alloy coarse grains on mechanical properties and fracture mechanism of Al5083-B4C tri-modal composite has been discussed. Al5083 alloy powders with 5 wt. % of boron carbide were milled for 36 hours and 25 and 50 wt. % of coarse grain (CG) Al2024 and Al5083 powders were added to the milled powders and then hot press under argon atmospher...
متن کاملUltra-Fine Grained Dual-Phase Steels
This paper provides an overview on obtaining low-carbon ultra-fine grained dual-phase steels through rapid intercritical annealing of cold-rolled sheet as improved materials for automotive applications. A laboratory processing route was designed that involves cold-rolling of a tempered martensite structure followed by a second tempering step to produce a fine grained aggregate of ferrite and ca...
متن کاملThe effect of temperature and strain rate on elongation to failure in nanostructured Al-0.2wt% Zr alloy fabricated by ARB process
A nano/ultra-fine grain Al-0.2wt% Zr alloy was produced by accumulated roll bonding (ARB) processafter 10 cycles. The fraction of high angle grain boundaries increased from 8% to 65.4% during 10passes during ARB process. This alloy was subjected to tensile test at different temperatures (523,573and 623 K) and strain rates (0.1 and 0.01 s-1). The optimum condition of temperature and strain rate ...
متن کامل