NMJ-4 High-strength Wear-resistant Refractory Castable is a cement-based, single-component dry mortar formulated for industrial applications requiring moderate wear resistance and stable thermal performance. It is composed of high-strength aluminate cement, high-performance mineral admixtures, abrasion-resistant aggregate, and specialized anti-crack additives. NMJ-4 offers an ideal balance between cost-efficiency and mechanical stability, making it suitable for secondary wear zones in boilers, kilns, and other thermal processing equipment.
Technical Specifications
| Parameter | Value |
|---|---|
| Al₂O₃ (%) ≥ | 75 |
| Bulk Density (g/cm³) ≥ | 2.8 |
| Cold Crushing Strength (MPa) ≥ | 110℃ × 24h: 901100℃ × 3h: 110 |
| Modulus of Rupture (MPa) ≥ | 110℃ × 24h: 151100℃ × 3h: 18 |
| Permanent Linear Change (1100℃ × 3h, %) | -0.2 ~ 0 |
| Room Temperature Wear Volume (cm³) ≤ | Not specified (custom on request) |
Key Features
Medium-duty Strength: Sufficient crushing and flexural strength for general industrial thermal zones
Stable Volume Performance: Minimal shrinkage under high temperatures, ensuring structural consistency
Good Castability: Compatible with manual or vibrated casting techniques
Thermal Stability: Designed to handle moderate thermal shock and temperature cycling
Balanced Performance-to-Cost Ratio: Suitable for industries balancing durability and budget
Typical Applications
Lining and maintenance of fluidized bed boiler components
Industrial air ducts, cyclone separators, and ash hoppers
Back-up layers or transition zones behind higher-performance refractories
Thermal insulation protection layers in furnaces and incinerators
Cement or steel plant components exposed to moderate mechanical wear
Production Details
NMJ-4 is manufactured using:
High-purity aluminate cement binders
Classified refractory aggregates for strength and density control
Industrial-grade additives to improve wear resistance and minimize cracking
Produced under automated batching and mixing systems to ensure consistency and quality control
Each batch is tested for strength, density, and thermal behavior before shipment.
Packing and Shipping Details
Packaging: 25kg or 50kg multi-layer moisture-proof paper bags
Bulk Packaging: 1-ton jumbo bags available for bulk projects
Palletization: Stretch-wrapped and palletized for container shipping
Frequently Asked Questions (FAQ)
Q1: What is the recommended installation method?
NMJ series castables are suitable for vibration casting or hand pouring. Mix with clean water (typically 5–7%) and avoid over-watering to ensure optimal strength and density.
Q2: How long should the castable dry before heating?
After pouring, let it air cure for at least 24 hours, then follow a stepwise heating curve to fully dry and sinter the material.
Q3. Can it be used in high-temperature areas with direct flame contact?
Yes. These castables are designed for high thermal resistance and mechanical integrity in flame-exposed zones, provided correct installation and preheating procedures are followed.
Q4: Are customized formulations available?
Absolutely. We provide tailored solutions based on operating conditions, installation method, or specific chemical resistance requirements.
Q5: What’s the key difference among NMJ-1 to NMJ-5?
The main differences are in alumina content, density, strength, and abrasion resistance. NMJ-1 is highest-grade; NMJ-5 is more economical for lighter-duty areas.
