Classification of Ceramic Raw Materials Questions and Answers

Answer: C

The name reflects the use of synthesised high-purity powders and the close control of composition and microstructure. Some advanced ceramics are fired lower than a porcelain, so temperature is not the distinguishing feature.

Answer: D

Having already been fired it does not shrink further, so it reduces the overall drying and firing shrinkage of the body. Refractories and heavy clay ware use it extensively for exactly that reason. Grog also opens the body and helps water escape during drying.

Answer: A

Both are true and the reason gives both benefits: large or thick pieces are the hardest to dry and fire without cracking, and grog addresses the shrinkage and the permeability together. Grog content rises with the section thickness of the ware.

Answer: B

Plasticiser, flux, filler and refractory describe what a material does rather than what it is, and one material may serve different roles in different bodies. This is generally the most useful way of thinking about a formulation.

Answer: C

Correct answer: False

The role depends on the body and the temperature it is fired to. Quartz is a filler in earthenware and partly dissolves into the melt in a porcelain fired higher; alumina stiffens a glaze and is a refractory in a kiln shelf; a clay is the plastic component in one body and part of the refractory bond in another. The classification describes what a material does in a particular body, not what it is.

Answer: D

Correct answer: ability to withstand high temperature without softening

Refractoriness is the defining property: the material must retain its strength and its shape at the working temperature of a furnace or kiln. That means a low content of fluxes - alkalis, iron, lime - and a high content of alumina, silica or magnesia. Refractory materials are neither cheap nor plastic, and nothing used in a furnace lining is soluble in water.

Answer: A

Twenty-five per cent of 400 kilograms is 100. Batch calculations of this kind are the daily arithmetic of a ceramic body shop and are usually done to the nearest kilogram. Recipes are normally written as percentages and scaled to the batch size.

Answer: B

Correct answer: more plastic and less white when fired

Ball clay is a sedimentary deposit: transport sorted it to a finer particle size, which is what makes it plastic, and along the way it collected organic matter and iron, which is what makes it fire cream or buff. China clay is residual, sitting where it weathered, so it is coarser, less plastic and much purer.

Answer: C

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason gives the necessity. China clay fires white but is too short to throw or cast well; ball clay works beautifully but darkens the fired body. Blending them lets the potter buy exactly as much plasticity as the forming method needs and no more colour than the ware can tolerate - and the ratio is one of the standard levers in body formulation.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: plastic against non-plastic is the primary functional division, and a material’s role varies between bodies. Statement 3 misdefines advanced ceramics, which are characterised by synthetic, high purity, closely controlled powders and by the properties engineered from them - not by firing temperature, which a traditional refractory may well exceed.