Semi-Rebonded Magnesia Chrome Brick

 

Introduction

 

Semi-rebonded magnesia-chrome bricks (also known as semi-fused bonded magnesia-chrome bricks) are refractory materials positioned between directly bonded magnesia-chrome bricks and fully fused rebonded magnesia-chrome bricks.

During high-temperature firing, some particles partially melt, forming localized crystalline networks, while retaining parts of the original direct bonding structure between particles.

These bricks are made from fused magnesia-chrome composite sand, fired at high temperatures with sintered magnesite, chrome ore, or pre-reacted magnesia-chrome sand. Compared with fully rebonded bricks, they exhibit better thermal shock resistance and are also characterized by low porosity, high high-temperature strength, and excellent slag resistance. They are widely used in the non-ferrous metal industry, serving as an intermediate product that combines the strengths of rebonded and directly bonded magnesia-chrome bricks.

Advantage

 

Thermal shock resistance: Superior to fully directly bonded bricks in environments with rapid temperature fluctuations, thanks to the stress-relieving effect of the partially fused structure.

Erosion resistance: A high-density layer formed in the molten areas slows the penetration of molten steel or slag. Performance is better than direct bonded bricks but slightly below that of fully fused bricks.

High-temperature strength:Local crystallization enhances load-bearing capacity, making these bricks suitable for intermittent high-temperature operations.

 

Zinfon Refractory Technology Co.,Ltd.

 

We provide one-stop services from technical consultation to design, production, and after-sales support.

Manufacturer Direct

Factory Prices

Premium Service

Customization Available

 

Physical and Chemical Specifications

1. Raw Material Preparation

Ingredient Selection:

Magnesia sand (MgO ≥ 95%) as the main aggregate for high-temperature strength and erosion resistance.

Chrome ore (Cr₂O₃ ≥ 40%) as fine powder to improve thermal shock and slag resistance.

Binders such as pulp waste or phosphates serve as temporary binders that form permanent bonds upon sintering.

Preprocessing:

Magnesia and chrome ore are crushed to a specific particle size (e.g., <3 mm) and mixed in a typical ratio of 70%–80% magnesia to 20%–30% chrome ore.

2. Molding and Drying

Molding Pressure: High-pressure hydraulic pressing (≥200 MPa) ensures uniform density (bulk density ≥ 2.8 g/cm³).

Drying: The green bricks are dried at 110–150°C for 24–48 hours to remove moisture and improve handling strength.

3. High-Temperature Firing (Key Step)

Firing Stages:

Low Temperature (600–800°C): Removes residual volatiles and stabilizes the green body.

Medium Temperature (1200–1400°C): Solid-state reaction between magnesia and chromite initiates spinel formation.

High Temperature (1500–1650°C):

Partial Fusion: Surfaces of some particles melt to form a glass phase, but full sintering does not occur (as in electrofused bricks).

Crystallization: Further growth of magnesite and chrome spinel crystals creates a hybrid "direct bonding + local melting" structure.

Temperature Control: Must be precisely managed (≤100°C/hour) to avoid cracking from thermal stress.

4. Post-Processing and Inspection

Cutting and Grinding: Bricks are shaped as needed (e.g., special bricks for slag lines in VOD furnaces).

Performance Testing:

Bulk density ≥ 2.85 g/cm³

Apparent porosity ≤ 18%

Compressive strength (20°C) ≥ 40 MPa

Thermal shock resistance (1100°C water quenching) ≥ 15 cycles

 

VOD Furnace (Vacuum Oxygen Decarburization Furnace)

 

Slag Line Area:

Directly resists high-temperature slag and steel erosion.

Partially fused structure forms a crystalline magnesite–Cr₂O₃ spinel network for enhanced penetration resistance.

Relieves thermal stress and reduces spalling.

Thickness: typically 80–100 mm (vs. 50–60 mm for conventional bricks).

 

Mid Furnace Wall (Buffer Zone):

Balances thermal expansion between working and permanent layers.

 

Tilting Mechanism Zone:

Withstands mechanical stress during tilting.

ZrO₂ (2%–5%) improves thermal shock resistance and prevents edge chipping.

 

Cement Kiln Transition Zone

Working Layer (gas-side exposure):

Resists alkaline gas and dust attack, and buffers thermal stress.

Local fused structure and crystalline spinel network improve penetration resistance.

Microporosity (5%–8%) is controlled to limit crack propagation.

Thickness: typically 50–70 mm (adjustable per kiln diameter).

 

Wheel Belt Contact Area:

Endures mechanical stress (compression and shear) from the pulley and cylinder interface.

Additions of ZrO₂ (3%–5%) or steel fiber enhance crack resistance and toughness.

 

 

Why chooes us?

 

01/Customized dimensions and shapes

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Customized Brick Shape

 

Provide Sample Sheets

1

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Mold Opening & Quotation

2

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Mold Opening & Sample Making

3

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Bulk Production Quotation

4

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Contract Signing

5

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Bulk Production

6

02/Delivery cycle and logistics

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Sea freight, land freight. Determine the mode of transportation according to the needs

About 30 days, customized products delivery time depends on the actual situation.

 

03/Customized packaging

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Customize your brand

Logo customization, custom fonts, taglines and messages for packaging, signage, websites or printed materials.

Take your brand to the next level, contact us today to discuss your project!

 

04/Purchase ZINFON refractory Bricks at Reasonable Prices

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The price of refractory bricks is a known key factor influencing customers' purchasing decisions. Therefore, we offer affordable refractory bricks for sale. Here are several reasons why ZINFON provides refractory bricks at competitive prices:

 

 

Factory price

By collaborating with ZINFON, we ensure that customers enjoy the ex-factory price of refractory bricks, reducing costs from middlemen or distributors. This allows customers to obtain the most cost-effective pricing directly from the source.

 

 

 

Low raw material cost

ZINFON is surrounded by abundant mineral resources. With these high-quality materials, customers can obtain products that are both affordable and excellent in performance.

 

 

 

Mass production

ZINFON possesses advanced production equipment and technologies, enabling the factory to achieve economies of scale and reduce unit production costs. Meanwhile, it ensures a continuous supply of high-quality products at preferential prices.

 

It is worth noting that while price is an important factor, it should not be the sole determinant of your purchasing decision. When buying refractory bricks from ZINFON, quality, reliability, and technical support are equally important considerations.

 

By choosing ZINFON as your supplier, you can access high-quality refractory bricks, a wide range of other refractory materials, and comprehensive support. Contact ZINFON Refractories immediately to discuss your specific requirements and obtain customized solutions!

 

How To Cooperate With Us?

7*24 hours online response

Provide professional after-sales protection‬

Our address

Qinghua Management Dist., Dashiqiao City, Yingkou City, Liaoning, China

Phone Number

+8613700131695

+8618540210631

E-mail

info@zinfon-refractory.com

 

 

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