Silica bricks are acid-resistant refractory bricks containing ≥93–96% SiO₂, manufactured from high-purity quartzite and fired at 1400–1500°C to develop a stable cristobalite-tridymite phase structure. With load softening points of 1640–1700°C, they are the standard refractory for glass tank furnace crowns, coke oven heating walls, and hot blast stove domes. Yes, all bricks made from natural clay contain some silica, but silica refractory bricks are a specialized industrial product engineered for sustained performance above 1600°C in acidic environments.
Zhengzhou Highland Refractory manufactures a complete series of silica bricks (SiO₂ ≥93%–96%) engineered specifically for acid-environment, high-temperature applications. Our silica brick grades cover the full service spectrum: from SK-34 standard profiles for hot blast stoves to high-density SK-40 grades for glass tank furnace crown linings. Each production batch undergoes load softening point testing (≥1650°C) and SiO₂ purity verification. We supply standard ISO sizes and custom-profiled bricks for complex furnace geometries.
Silica bricks, made primarily from high-purity silica (SiO₂), are among the most critical refractory materials used in high-temperature industrial processes.
Silica bricks, made primarily from high-purity silica (SiO₂), are among the most critical refractory materials used in high-temperature industrial processes.
This page covers silica refractory bricks (industrial furnace bricks with ≥93% SiO₂ for glass furnaces, coke ovens, and hot blast stoves). These are NOT the same as calcium silicate bricks (autoclaved sand-lime construction bricks), sodium silicate bricks, sodium silicate fire brick, or mineral silicate paint — which are building materials, not refractory products. Highland Refractory supplies silica refractory bricks for industrial high-temperature applications only.
Silica brick performance varies significantly by SiO₂ content, apparent porosity, and load softening point. Match your furnace type to the correct grade below.
| Furnace / Application | Recommended Grade | SiO₂ Content | Load Softening Point | Key Requirement |
|---|---|---|---|---|
| Coke Oven | SK-38 / SK-40 | ≥95% | ≥1680°C | Volume stability, creep resistance |
| Glass Tank Furnace Crown | SK-40 Dense | ≥96% | ≥1700°C | Low porosity, no glass contamination |
| Hot Blast Stove | SK-34 / SK-36 | ≥93% | ≥1650°C | Thermal cycling resistance |
| Ceramic / Tunnel Kiln | SK-34 Standard | ≥93% | ≥1640°C | Cost-effective, acid slag resistance |
In addition to dense silica refractory bricks for hot-face structural linings, Highland Refractory supplies silica insulation bricks — a lightweight, porous variant designed for backup insulation layers behind dense silica brick linings in glass furnaces and coke ovens.
Silica insulation bricks are manufactured with controlled porosity (typically 40–55% apparent porosity), resulting in bulk densities of 1.0–1.2 g/cm³ — roughly half that of dense silica bricks (2.1–2.3 g/cm³). This porosity dramatically reduces thermal conductivity to 0.4–0.7 W/(m·K) at 1000°C, cutting heat loss through the furnace shell while maintaining compatibility with the hot-face silica brick's thermal expansion behavior.
| Property | Dense Silica Brick (SK-34 to SK-40) | Silica Insulation Brick |
|---|---|---|
| SiO₂ Content (%) | ≥93 – 96 | ≥90 |
| Bulk Density (g/cm³) | 2.10 – 2.30 | 1.00 – 1.20 |
| Apparent Porosity (%) | 18 – 24 | 40 – 55 |
| Cold Crushing Strength (MPa) | ≥ 30 | ≥ 5 |
| Thermal Conductivity (W/m·K, 1000°C) | 1.2 – 1.5 | 0.4 – 0.7 |
| Max Service Temperature (°C) | 1600 – 1700 | 1500 – 1550 |
| Application | Hot-face lining (crown, walls, regenerator) | Backup insulation layer behind dense silica brick |
Silica insulation bricks are not structural refractories — they cannot bear the mechanical loads of a crown or wall. Their role is to reduce the temperature gradient across the lining system, protecting the furnace steel shell from overheating while improving overall energy efficiency. For hot-face positions, always use dense silica refractory bricks.
Backed by decades of expertise, Highland Refractory delivers tailored silica refractory brick solutions across steel, cement, glass, and petrochemical industries. The following silica bricks uses represent the primary industrial applications where our products deliver measurable performance advantages.
The crown and superstructure of a float glass or container glass furnace operate continuously at 1580–1650°C under corrosive alkali vapor (Na₂O, K₂O). Standard refractories contaminate the glass melt and degrade within months under these conditions. Highland's SK-40 Dense Grade silica brick (SiO₂ ≥96%, apparent porosity ≤18%) delivers a near-zero contamination profile and maintains dimensional stability through a full campaign life of 8–12 years. Its ultra-low iron content (<0.3% Fe₂O₃) is critical for preventing glass discoloration in high-clarity float glass production. Custom crown arch profiles are available to match your furnace geometry with dimensional tolerance ±0.5mm.
Coke oven heating walls cycle between 1250°C and 1450°C thousands of times over a campaign life spanning 25–30 years. The primary failure mode is creep deformation — walls bow inward under sustained thermal load, jamming the coke-pushing machine and triggering costly unplanned downtime. Highland's SK-38 / SK-40 coke oven grade silica brick is engineered with a controlled cristobalite-tridymite phase ratio that minimizes volume change above 600°C, delivering a creep rate of ≤0.5% at 1600°C × 50h. Consistent brick geometry with dimensional tolerance ±0.5mm ensures tight joint integrity throughout the campaign, preventing gas leakage between heating cells.
The dome and upper combustion chamber of a blast furnace hot blast stove alternate between blast and on-gas cycles at 1300–1450°C, creating severe thermal shock conditions that cause conventional bricks to spall and crack prematurely. Highland's SK-34 / SK-36 hot blast stove grade leverages the unique low thermal expansion characteristic of silica above 600°C — a result of the cristobalite-tridymite polymorphic transition — to absorb cycling stress without structural damage. With thermal conductivity of 1.2–1.5 W/(m·K) at 1000°C, it maintains efficient heat transfer to the blast air, directly supporting hot metal production output and energy efficiency targets.
Roof structures in ceramic tunnel kilns and shuttle kilns must simultaneously bear their own suspended weight at 1250–1380°C while resisting alkali flux vapor (K₂O, Na₂O) rising from ceramic ware below. Highland's SK-34 Standard Grade silica brick offers the optimal cost-performance balance for this environment: a load softening point of ≥1640°C prevents arch deformation under sustained load, while the dense silica matrix resists alkali flux infiltration without requiring premium-grade material costs. Custom arch and wedge profiles are available for both straight and curved kiln roof geometries.
One of the most common questions from furnace engineers and procurement teams: do bricks contain silica? The short answer is yes — virtually all bricks made from natural clay or mineral raw materials contain silica (SiO₂) in some form. However, the silica content varies dramatically between ordinary construction bricks and industrial silica refractory bricks.
| Brick Type | SiO₂ Content | Is There Silica in Bricks of This Type? |
|---|---|---|
| Common Clay Brick (construction) | 50 – 65% | Yes — silica is a natural component of clay |
| Fire Clay Brick | 50 – 70% | Yes — silica from fireclay raw material |
| High Alumina Brick | 20 – 40% | Yes — but as a secondary component to Al₂O₃ |
| Silica Refractory Brick | ≥93 – 96% | Yes — silica is the dominant and intentional primary phase |
| Mullite Brick | 15 – 30% | Yes — as part of the 3Al₂O₃·2SiO₂ compound |
So when someone asks "is there silica in bricks?" — the answer is always yes for any clay-based or mineral-based brick. The critical distinction is the silica content level and the purity of the silica phase. Silica in bricks at the 50–65% level (common clay bricks) simply reflects the natural composition of the raw clay. Silica in bricks at ≥93% (silica refractory bricks) is an engineered, intentional concentration that delivers specific high-temperature properties: acid resistance, load softening point above 1650°C, and thermal expansion behavior suited for glass furnace and coke oven applications.
For industrial furnace operators, the question is not whether bricks contain silica, but whether the silica content is sufficient and pure enough for the service temperature and chemical environment. That is where silica refractory bricks — with their ≥93% SiO₂ content and controlled cristobalite-tridymite phase — outperform all other brick types.
Highland silica refractory bricks are available in four standard grades. All grades share the same fundamental silica-based mineralogy but differ in purity, density, and performance characteristics.
| Technical Property | SK-34 Standard | SK-36 | SK-38 | SK-40 Dense |
|---|---|---|---|---|
| SiO₂ Content (%) | ≥93 | ≥94 | ≥95 | ≥96 |
| Al₂O₃ Content (%) | ≤1.5 | ≤1.2 | ≤1.0 | ≤0.8 |
| Fe₂O₃ Content (%) | ≤1.5 | ≤1.2 | ≤1.0 | ≤0.3 |
| Bulk Density (g/cm³) | 2.10 – 2.20 | 2.15 – 2.25 | 2.20 – 2.28 | 2.25 – 2.30 |
| Apparent Porosity (%) | ≤24 | ≤22 | ≤21 | ≤18 |
| Cold Crushing Strength (MPa) | ≥30 | ≥35 | ≥40 | ≥50 |
| Refractoriness Under Load (°C) | ≥1640 | ≥1650 | ≥1680 | ≥1700 |
| Thermal Expansion at 1000°C (%) | 1.2 – 1.4 | 1.2 – 1.4 | 1.1 – 1.3 | 1.0 – 1.2 |
| Primary Application | Tunnel kiln, hot blast stove (lower zone) | Hot blast stove dome | Coke oven heating walls | Glass furnace crown, coke oven (high-duty) |
| Property | Silica Refractory Brick | Fire Clay Brick | High Alumina Brick |
|---|---|---|---|
| Primary Chemistry | SiO₂ ≥93% | Al₂O₃ 30–48%, SiO₂ 50–70% | Al₂O₃ ≥48% |
| Bulk Density (g/cm³) | 2.10 – 2.30 | 2.00 – 2.40 | 2.40 – 2.70 |
| Refractoriness Under Load (°C) | 1640 – 1700 | 1300 – 1450 | 1450 – 1550 |
| Acid Slag Resistance | Excellent | Moderate | Good |
| Thermal Shock Resistance | Moderate (above 600°C: excellent) | Good | Excellent |
| Silica Brick Melting Point (°C) | ~1710 (softening), pure SiO₂: 1723 | ~1600 | ~1790 |
| Best For | Glass furnaces, coke ovens, acid environments | General furnace linings, moderate temperature | High-temperature load-bearing zones |
Silica fire bricks are the only choice when the application involves both acid slag and temperatures above 1600°C — fire clay bricks soften and fail under these conditions, and while high alumina bricks can handle the temperature, they do not match silica's acid resistance or its unique low thermal expansion behavior above 600°C that makes silica fire bricks ideal for glass furnace crowns.
Silica bricks price depends on four primary factors: SiO₂ purity grade, brick density (standard vs. dense), dimensional complexity (standard ISO shapes vs. custom arch/wedge profiles), and order volume. Because industrial furnace projects specify different grades for different zones — SK-34 for backup areas, SK-40 Dense for crown hot-face — a single standardized silica bricks price list does not accurately reflect project budgeting.
As a general reference for 2026 budgetary planning:
| Grade | Indicative Price Range (USD/ton) | MOQ |
|---|---|---|
| SK-34 Standard | $280 – $420 | 5 tons |
| SK-36 | $320 – $460 | 5 tons |
| SK-38 | $380 – $550 | 5 tons |
| SK-40 Dense | $450 – $680 | 5 tons |
| Silica Insulation Brick | $350 – $520 | 3 tons |
| Custom Profiles (arch, wedge, keystone) | +15% – 30% over base grade | 5 tons |
These prices are indicative reference ranges only. Actual silica bricks price varies with raw material market conditions, freight destination, and specific dimensional requirements. Sourcing directly from Highland Refractory eliminates trading-company margins — contact our sales team with your specifications and required volume for a firm quotation within 24 hours.
Highland's silica bricks are produced from premium quartzite ore with SiO₂ content controlled at ≥93%–96% across all grades. Higher purity directly translates to a higher load softening point (≥1650°C–1700°C) and superior resistance to acid slag attack. For glass furnace operators, this means crown linings that last 8–12 years without contaminating the melt. For coke oven managers, it means heating walls that hold dimensional stability through 25–30 years of thermal cycling — eliminating the premature replacement costs that erode profitability.
The critical failure risk of silica brick is uncontrolled polymorphic phase transformation below 600°C, which causes sudden volume expansion and structural cracking during heat-up. Highland's sintering process precisely controls the cristobalite-tridymite ratio in each batch, ensuring stable phase composition and minimizing residual quartz content to ≤1.5%. The result: safe, predictable thermal expansion behavior during kiln commissioning and scheduled shutdowns — protecting both your refractory lining and your furnace shell from expansion-induced damage.
In coke ovens and glass furnaces, even a 0.5mm dimensional deviation accumulates across hundreds of bricks, creating gaps that allow gas leakage, heat loss, and accelerated corrosion at joint faces. Highland operates CNC grinding and precision mold pressing to hold dimensional tolerances of ±0.5mm across all standard and custom profiles — including wedge, arch, and keystone shapes. Every batch undergoes dimensional inspection before shipment, with full measurement records issued per order.
Industrial furnace projects rarely need just one brick shape. Highland supplies the complete silica brick series — SK-34 / SK-36 / SK-38 / SK-40 standard and dense grades — alongside custom-profiled bricks for crowns, arches, walls, and expansion joints, all from a single manufacturing facility. This eliminates multi-supplier coordination risks: inconsistent raw material batches, mismatched thermal expansion coefficients, and split quality accountability. One supplier, one certificate, one point of contact for your entire furnace refractory package.
Yes. All clay-based and mineral-based bricks contain some silica. Common clay bricks have 50–65% SiO₂, while silica refractory bricks are engineered with ≥93% SiO₂ for high-temperature acid-resistant service.
Silica bricks do not have a single melting point — they soften gradually. The refractoriness under load (load softening point) ranges from 1640°C (SK-34) to 1700°C (SK-40 Dense). Pure SiO₂ melts at 1723°C.
Primarily for glass tank furnace crowns, coke oven heating walls, hot blast stove domes, and ceramic kiln roofs — anywhere with acid slag and temperatures above 1600°C.
Silica brick has ≥93% SiO₂ and a load softening point of 1640–1700°C. Fire clay brick has 50–70% SiO₂ with Al₂O₃ as a co-component and softens at 1300–1450°C. Silica brick is superior for acid environments.
Yes. Ordinary clay construction bricks typically contain 50–65% silica from natural clay. This is unrelated to silica refractory bricks, which are industrial products with ≥93% SiO₂.
A lightweight silica brick (1.0–1.2 g/cm³) with 40–55% porosity, used as backup insulation behind dense silica brick linings to reduce heat loss. Not for hot-face structural use.
Completely different products. Silica refractory bricks are fired at 1400–1500°C for industrial furnaces (≥93% SiO₂). Calcium silicate bricks are autoclaved sand-lime construction bricks for building walls, not refractory use.
In silica refractory bricks, the high SiO₂ content creates acid resistance and a high load softening point. In ordinary clay bricks, silica is simply a natural component of clay with no engineered function.
Yes. We machine wedge, arch, and keystone profiles to ±0.5mm tolerance. Monthly capacity reaches 500 tons with OEM/white-label support.
MOQ is 5 tons for standard grades (3 tons for insulation bricks). Standard grades ship in 7–15 days; custom profiles require 20–30 days. Shipping from Qingdao port worldwide.
Full Grade Coverage: SK-34 / SK-36 / SK-38 / SK-40 standard and dense grades, plus silica insulation bricks — all held in stock.
Custom Profiling: Wedge, arch, and keystone shapes machined to ±0.5mm dimensional tolerance. Volume Capability: Monthly output up to 500 tons; OEM/white-label supply supported. Certification: ISO 9001:2015 certified; test reports (XRF, load softening point) issued per order.
Submit your specifications, required grades, and volume. Our industrial sales team will issue an official quotation within 24 hours.
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Silica bricks, made primarily from high-purity silica (SiO₂), are among the most critical refractory materials used in high-temperature industrial processes.
High Alumina Silica Brick (also called alumina-silicate firebrick) is a high-performance refractory material made from Al₂O₃–SiO₂ systems. Engineered for equipment operating at 1400–1750°C, these bricks deliver excellent thermal stability, slag resistance, structural strength, and extended service life in harsh industrial environments. Highland Refractory supplies premium-grade high alumina silica bricks with stable chemical compositions, strict dimensional tolerances, and complete customization for steel, cement, glass, ceramics, petrochemical, and power industries.
Alumina silica refractory bricks are high-temperature ceramic materials mainly composed of Al₂O₃ (alumina) and SiO₂ (silica). These bricks are engineered to withstand extreme heat, chemical corrosion, mechanical stress, and thermal shock, making them the most widely used refractory products in furnaces and kilns across steel, cement, glass, and petrochemical industries.
Highland Refractory’s asbestos-free calcium silicate insulation boards — bulk density 230-800 kg/m³, thermal conductivity ≤0.08 W/(m·K). Two temperature grades: 650°C for cement kiln & boiler back-up lining, and 1000°C for smelting furnace & glass tank insulation. Factory-tested dimensional stability, easy on-site cutting, factory-direct pricing.
Calcium Silicate Insulation Board is a high-performance, lightweight thermal insulation material designed to provide exceptional fire resistance and superior thermal insulation in high-temperature industrial applications. This non-asbestos product, primarily made from a blend of silica (SiO₂) and calcium (CaO) along with reinforcing fibers, is widely used across multiple industries for its remarkable heat-resistant properties. It is ideal for applications that require continuous exposure to temperatures as high as 1000ºC. This product offers not only excellent insulation but also superior mechanical strength and durability, making it suitable for a wide range of applications, including steel furnaces, chemical processing units, boilers, kilns, and energy systems. Available in various thicknesses and dimensions, calcium silicate insulation boards provide an efficient solution for meeting the challenging demands of high-temperature environments.
