What is meant by Linear Change in refractory testing?

Linear change in refractory testing refers specifically to the measurement of the dimensions of a specimen after it has been subjected to heating. This is a critical assessment, as it provides insight into how the refractory material behaves under thermal conditions, which is essential for determining its performance in high-temperature applications.

When refractory materials are exposed to heat, they can expand or shrink, leading to changes in size that can affect their functionality and structural integrity. By measuring these dimensional changes, engineers and quality control personnel can evaluate the material's ability to withstand thermal stresses and dimensional stability, which are vital for ensuring that refractory linings can hold up under operational conditions.

The other options, while they may be related to the characteristics of refractory materials, do not accurately define linear change. Weight reduction refers to loss of material rather than dimensional stability, color change does not inform about the thermal performance, and density variation pertains to material composition rather than its linear dimensions post-heating.