Characterisation Techniques for Raw Materials Questions and Answers

Answer: C

A push-rod follows the length of a specimen as the temperature rises, so expansion coefficient and any sudden change are both measured. Glaze fit calculations depend directly on such measurements for body and glaze alike.

Answer: D

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

Both are true and the reason gives the purpose. Crazing occurs when the glaze contracts more than the body and ends in tension; shivering when it contracts less and ends in excessive compression. Both are expansion mismatches, so both are predicted by measuring the two expansion curves on a dilatometer before committing the glaze to production - the glaze being aimed at a slightly *lower* expansion than the body so that it finishes in mild compression.

Answer: A

Each occupies its own temperature range, and a firing schedule is built around that sequence. Reading a thermal analysis trace from left to right is effectively reading the same list in order. Each event has its own signature on the trace.

Answer: B

Correct answer: X-ray diffraction

Diffraction identifies crystalline phases by their atomic arrangement and reports no elemental analysis at all. The other three are all elemental methods: inductively coupled plasma spectrometry and atomic absorption work on a solution, and X-ray fluorescence on a fused bead or pressed pellet. The pair of questions - which phases, which elements - needs both kinds of instrument.

Answer: C

The difference in mass is expressed as a percentage of the original and includes water, carbon dioxide and any organic matter. It is one of the simplest and most informative tests available on an incoming raw material.

Answer: D

The loss of 0.650 grams on a starting mass of 5.000 grams is thirteen per cent. Expressing the remainder rather than the loss is the mistake this calculation most often produces. The figure is always quoted as the loss rather than the residue.

Answer: A

Correct answer: quartz remaining unchanged in the sample

Loss on ignition is a weight loss, so anything that stays put contributes nothing. Quartz is stable to well above the ignition temperature and simply remains. The genuine contributors are the hydroxyl water leaving the clay lattice, which usually dominates, carbon dioxide from any carbonates, and organic matter burning away.

Answer: B

An image of the particles reveals morphology that no equivalent-diameter measurement conveys, such as whether they are platy, tubular or equiaxed. Fitted with an X-ray detector it will also give a local elemental analysis.

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 purpose. The electron beam excites characteristic X-rays from whatever it strikes, and an energy dispersive detector analyses them, so the operator can point at one particle in the image and ask what it is made of. That combination of morphology and composition on the same spot is what makes the technique so useful for identifying contaminants and inclusions.

Answer: D

Correct answer: A-2, B-4, C-1, D-3

Four questions and four instruments. Which phases are present is diffraction. Which elements are present is X-ray fluorescence. What shape the particles are is electron microscopy. And how much is lost on firing is the loss on ignition, which needs nothing more than a furnace and a balance. Choosing the right instrument for the question is most of what characterisation amounts to.