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متالوژی::
خاکستر استخوان
This bone ash contains a little organic matter which, combined with fine size, gives it some plasticity.
The raw material mix consisting of 45-50% bone ash, 25-30% china clay, 25-30% feldspar (flux) and about 5% ball clay (plasticizer) is first mixed with water and ground; then the slurry is de-watered by filter-pressing, shaped according to the product desired and slowly dried, and finally biscuit fired at a temperature lying within a carefully controlled short range of 1250-1300�C.
The bone ash in the right proportion acts as a flux, but when in excess, it increases refractoriness.
For making bone ash, cattle bone is first crushed, washed and then subjected to heating in a highly oxidized condition by slowly increasing the temperature to 900-1000� C, whereby most of the organic matter is removed.
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