Quality evaluation of refractories by spray testing: In refractory testing, the “spray test” is primarily used to determine which performance characteristic of a lining material?

Introduction / Context:
Refractory linings in steel and non-ferrous metallurgy face aggressive slags that can penetrate and erode the brick microstructure. Laboratory tests simulate such conditions. The “spray test” (or slagging test variants) assesses how easily liquid slag infiltrates a refractory surface.

Given Data / Assumptions:

• Test type: spray test simulating slag contact in service.
• Materials: common metallurgical refractories (e.g., alumina, basic bricks).
• Outcome: qualitative/quantitative measure of slag penetration depth/extent.

Concept / Approach:
Under high temperatures, slag can wet pore walls and advance into the lining, weakening it. Tests that expose a hot refractory face to a slag spray evaluate its resistance to this ingress. Lower penetration depth implies better performance against slag attack and improved service life in slag-wetted zones.

Step-by-Step Solution:
Identify what the test emulates: hot, flowing slag contacting refractory surfaces.Recognize measured outcome: depth or severity of slag infiltration.Conclude: spray test is for resistance to slag penetration.

Verification / Alternative check:
Standards and plant test protocols distinguish between CO-attack tests (reducing atmospheres), RUL tests (creep under load), and re-firing dimensional stability tests, none of which match “spray” conditions.

Why Other Options Are Wrong:

• Resistance to CO attack: different test environment (reducing gas), not slag spray.
• RUL: measures softening/creep under load, unrelated to penetration.
• Permanent linear change: dimensional stability test after heat treatment, not slag ingress.

Common Pitfalls:

• Confusing general “slag attack” with creep or thermal shock tests.
• Assuming one test covers all failure modes; each property requires a dedicated test.

Final Answer:
resistance to slag penetration