Reason for using silicon carbide (SiC) refractories in zinc smelting furnaces, muffle furnaces, and tunnel kiln supports: their refractoriness is approximately of the order of which temperature (°C)?

Introduction / Context:
Silicon carbide (SiC) refractories are chosen for applications requiring high strength at temperature, excellent thermal-shock resistance, and rapid heat transfer. Typical installations include zinc smelting furnaces, muffle furnaces, and kiln furniture in tunnel kilns. The question seeks the approximate order of their refractoriness as commonly stated in refractory engineering practice.

Given Data / Assumptions:

• “Refractoriness” refers to resistance to softening or deformation at high temperature.
• We refer to the order-of-magnitude value cited in engineering selections rather than absolute melting points.
• Service environments are oxidizing to neutral at high temperature, with thermal cycling.

Concept / Approach:
SiC exhibits very high hot strength and resists creep up to elevated temperatures. In design tables and selection guides, SiC refractoriness is often cited around the order of 2200°C. While SiC’s sublimation occurs at even higher temperatures under inert conditions, the practical engineering description associates SiC with refractoriness on the order of ~2200°C, supporting its use in the listed furnaces and kiln fittings.

Step-by-Step Solution:
Recall practical refractoriness indices for SiC products used industrially.Match with standard tabulated “order of” values.Select 2200°C as the representative order for SiC refractoriness.

Verification / Alternative check:
Product datasheets and refractory handbooks list SiC with very high softening temperatures and service limits consistent with an order-of-2200°C refractoriness figure for selection purposes.

Why Other Options Are Wrong:
1800°C / 2000°C: too low to represent the conventional “very high” refractoriness attributed to SiC.2400°C / 2700°C: these values approach sublimation or idealized limits; engineering tables typically quote ~2200°C as the order figure.

Common Pitfalls:
Confusing practical refractoriness (RUL/PCE context) with thermodynamic sublimation points.Ignoring oxidation or binder effects that limit service temperature below theoretical maxima.

Final Answer:
2200