Classification of Ceramic Raw Materials Questions and Answers

Answer: A

Correct answer: True

A natural deposit is the product of a particular geological history, so its composition, particle size and impurity content vary between deposits, between parts of one deposit and over time as a quarry advances. That variability is why raw materials are analysed on receipt, why blending beds and stockpiles exist, and why a body recipe is adjusted continuously rather than fixed.

Answer: B

Correct answer: consistency and purity matter more than cost

Synthetic powders are made to a specification - a stated purity, a controlled particle size distribution, a known phase - and they deliver it batch after batch. Where the property required depends on that control, as in a structural or electronic ceramic, the higher price is worth paying. Where it does not, it is not, as the next item says.

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 economics. A synthetic powder costs many times what a quarried clay does, and a floor tile or a sanitary fitting does not need submicron control of particle size to perform its function. Natural materials therefore remain the sensible choice for traditional ware, with variability managed by blending and by adjusting the recipe rather than by buying it away.

Answer: D

Earthenware retains open porosity and must be glazed to be watertight, whereas porcelain vitrifies and is impervious in itself. The difference lies in the body composition and firing temperature rather than in the shaping.

Answer: A

Earthenware keeps appreciable open porosity after firing, so an unglazed piece leaks. Porcelain vitrifies to near zero water absorption and is watertight even where the glaze is missing. A chipped porcelain plate remains usable, whereas chipped earthenware absorbs.

Answer: B

Dividing 12 by 0.2 gives 60. Water absorption is the standard test that separates the classes of whiteware and appears directly in the product standards. Absorption is measured by boiling a fired test piece and weighing it.

Answer: C

It is fired high enough to close the porosity but contains too much iron and other impurity to be translucent. Its toughness makes it the traditional choice for kitchen and tableware in heavy use. Its density also makes it resistant to chipping in service.

Answer: D

The first two are correct. The third has the order wrong, since stoneware is vitrified and denser than earthenware while stopping short of the translucency of porcelain. The three classes form a sequence of increasing vitrification.

Answer: A

Calcined animal bone provides calcium phosphate, which gives the body its whiteness and translucency at a comparatively modest firing temperature. The proportion is typically around half the body. Bone china is the traditional English contribution to whiteware bodies.

Answer: B

Standards define the classes by absorption limits, which is a measurable property rather than a matter of description. Shaping method and decoration are independent of the class the body falls into. A slip cast and a pressed piece of the same body are the same class.