High-Temperature Quartz Glass for Industrial Thermal Processing
FGQuartz supplies high-temperature quartz glass for furnaces and heating systems: infrared heater envelopes, furnace process tubes, thermocouple protection tubes and observation windows. With continuous service to roughly 1200°C — well above borosilicate glass and most ceramics — and near-zero thermal expansion, these parts withstand rapid heating and cooling.
When industrial processes push beyond the limits of borosilicate glass, most ceramics, and engineering polymers, high-temperature quartz glass takes over. Fused silica operates continuously at temperatures that would melt aluminium and warp steel furnace fixtures — while remaining chemically inert to the aggressive gases and corrosive atmospheres that accompany extreme heat. FGQuartz has supplied industrial high-temperature quartz glass to manufacturers, process engineers, and research institutions across 40+ countries since 2005.
Why Quartz Glass Outperforms Alternatives at High Temperature
Near-Zero Thermal Expansion
The thermal shock resistance of high-temperature quartz glass is a direct result of its near-zero coefficient of thermal expansion. When other materials heat rapidly, differential expansion between the hot outer surface and cooler interior generates cracking stresses. Fused silica’s expansion is so low that rapid heating and cooling cycles that would shatter borosilicate or ceramics leave quartz undamaged. This is why quartz furnace tubes survive being loaded into a hot furnace and removed to ambient air without cracking — a cycle that borosilicate glass cannot survive.
Chemical Resistance at Elevated Temperature
Industrial process gases — chlorine, hydrogen chloride, hydrogen, carbon monoxide, hydrocarbons, and inert gases — can all be used inside high-temperature quartz glass tubes without significant attack on the glass. This broad chemical compatibility makes industrial quartz glass the standard process tube material for chemical vapour deposition, thermal diffusion, metal heat treatment, and catalytic test reactors. Alternative materials would either react with the process chemistry or introduce contamination that would compromise the process result.
Optical Transparency for Infrared Heating
Clear fused silica transmits infrared radiation efficiently from the near-UV through to 3.5 µm in the near-infrared. This makes high-temperature quartz glass the universal envelope material for industrial infrared heaters — the heating element inside the tube radiates energy directly through the quartz wall to the workpiece being heated. No other affordable material provides this combination of infrared transparency and the high-temperature stability needed to survive sustained operation with an active heating element inside.
Extreme Thermal Stability
Continuous service to 1200 °C and short-term excursions to 1300 °C — beyond the capability of borosilicate glass, most engineering polymers, and many ceramics. The softening point of fused silica lies above the melting point of aluminium.
Exceptional Thermal Shock Resistance
Near-zero coefficient of thermal expansion means rapid heating and cooling cycles — even direct flame impingement — do not crack or fracture high-temperature quartz glass components. This is the property that makes quartz furnace tubes and heater envelopes practical in real industrial environments.
Chemical Inertness
Resistant to most mineral acids, oxidants, halogens, and industrial process gases at elevated temperatures. Industrial quartz glass does not leach metals or reactive species into the process environment — critical for heat treatment furnaces and analytical applications where contamination would compromise the result.
Electrical Insulation at Temperature
Fused silica maintains excellent electrical insulation at temperatures where polymer insulators fail. This property makes high-temperature quartz glass the standard material for heating element support rods, electrode isolation sleeves in plasma systems, and high-voltage feed-through insulators in vacuum equipment.
High-Temperature Quartz Glass Products
FGQuartz manufactures the core range of industrial high-temperature quartz glass components from our Lianyungang facility. Standard dimensions ship from stock; custom dimensions and fabricated assemblies are produced to drawing with no minimum order quantity.
Quartz Furnace Tubes
Clear and opaque fused silica process tubes for horizontal and vertical tube furnaces used in heat treatment, CVD coating, catalyst testing, materials synthesis, and annealing. Standard diameters for the major tube furnace platforms; custom lengths, wall thicknesses, and end configurations to drawing. Quartz furnace tubes are available with ground flat ends for O-ring face sealing, flame-welded flanges, and closed-end configurations for sealed-atmosphere processing.
Infrared Quartz Heater Tubes
Clear fused silica heater envelopes for short-wave and medium-wave infrared industrial heating systems. The infrared quartz heater tube transmits the radiation generated by the enclosed heating element through its wall to the workpiece, achieving energy-efficient surface heating for curing, drying, forming, and annealing applications in automotive, packaging, food processing, and textile manufacturing. Standard diameters for major IR heater manufacturers; twin-tube and custom configurations to order.
Thermocouple Protection Tubes
Single-bore and double-bore quartz thermocouple protection tubes for temperature measurement in corrosive, reactive, or chemically sensitive process environments. The quartz tube isolates the thermocouple sensing junction from the process atmosphere while conducting heat efficiently enough for accurate temperature measurement — a function that metal protection tubes cannot perform when the process gas would attack or contaminate the metal. Closed ends are formed by oxy-hydrogen flame sealing; flanged thermowell versions for pressurised vessel insertion are machined from solid quartz.
High-Temperature Observation Windows
High-temperature quartz glass sight windows for direct observation inside industrial furnaces, combustion chambers, and reactors. The window must withstand the temperature differential between the furnace interior and the cooler external environment, the infrared radiation from the furnace heating elements, and — in some applications — corrosive furnace atmospheres. The low thermal expansion of fused silica minimises the thermal stress at the window mounting edge, preventing the edge cracking that is common with higher-expansion glass alternatives. Circular and rectangular formats; polished optical-grade for pyrometry applications.
Opaque Quartz Furnace Liners
Opaque fused silica tubes and liners for thermal insulation between the hot process zone and the furnace heating elements. Unlike clear fused silica, opaque quartz contains microscopic voids that scatter and absorb infrared radiation rather than transmitting it. This gives opaque quartz low surface emissivity, making it an effective thermal insulator and radiant heat barrier. Opaque quartz liners in tube furnaces improve temperature uniformity along the tube length by reducing radiant heat exchange between the process tube and the furnace heating elements. Single-zone and multi-zone configurations in standard furnace-compatible diameters.
Custom High-Temperature Assemblies
Complex industrial quartz glass assemblies combining CNC-machined tube bodies, flame-welded side ports and flanges, and precision-ground sealing faces are produced to customer drawings. Plasma reactor electrode insulators, combustion chamber liner systems, industrial gas sampling probe assemblies, and multi-zone furnace tube configurations are standard custom items for the industrial heating and chemical processing sectors. Drawings accepted in DXF, STEP, IGES, or PDF format; prototype quantities from a single piece.
Industrial Quartz Glass Across Thermal Processing Sectors
High-temperature quartz glass serves a broader range of industrial applications than any other glass type. Select any application to understand the specific role quartz glass plays and why it outperforms alternatives in that environment.
Infrared Heating & Industrial Curing
Industrial infrared heater systems use quartz heater tubes to enclose resistive heating elements and transmit their thermal radiation output to the workpiece being heated. Short-wave infrared systems operating with filament temperatures above 2000 °C require clear fused silica envelopes with maximum transmission in the 0.7–2 µm range. Applications include automotive paint curing ovens, powder-coat curing systems, plastic thermoforming, textile heat-setting, food surface treatment, and printed circuit board solder reflow. The FGQuartz infrared quartz heater tube range covers standard diameters for major IR heater OEMs, with twin-tube and custom configurations available to specification.
Tube Furnaces & Heat Treatment
Industrial tube furnaces for metal heat treatment — bright annealing, hydrogen reduction, normalising, and sintering — use quartz process tubes as the containment vessel for the controlled atmosphere in the heated zone. Quartz furnace tubes are chosen because they can be sealed gas-tight at both ends, withstand the process temperature, and do not react with the process atmosphere or contaminate the workpiece surface with the metallic impurities that metal tube alternatives would introduce. Hydrogen bright annealing of precision components, precious metal annealing, and ceramic sintering are common high-temperature quartz glass tube furnace applications.
Chemical Processing & CVD Reactors
Chemical vapour deposition of hard coatings on metal cutting tools, catalytic test reactors for chemical synthesis research, and high-temperature gas-phase reaction systems use quartz reactor tubes and vessels because fused silica resists chemical attack by the halide and reactive gas chemistries used in these processes at the temperatures required for the reactions to proceed. The chemical inertness of industrial quartz glass prevents the reactor wall from catalysing side reactions that would compromise the selectivity and yield measurements in catalytic test work.
Plasma Processing Systems
Atmospheric plasma jets, radio-frequency plasma torches used in ICP-OES and ICP-MS analytical instruments, and industrial plasma treatment systems all use quartz glass chambers and torch tubes because fused silica uniquely provides RF transparency for inductive plasma coupling, chemical resistance to the reactive plasma species, and thermal stability at the extreme temperatures in the plasma periphery. ICP plasma torch assemblies use high-temperature quartz glass specifically because the material simultaneously provides electrical insulation for the electrode structure and thermal resistance to the plasma energy.
Food Processing & Pharmaceutical
Food processing infrared ovens use quartz heater tubes for surface browning, pasteurisation, and dehydration applications where direct contact with heating surfaces is not acceptable. Pharmaceutical manufacturing uses high-temperature quartz glass components in depyrogenation tunnels, dry heat sterilisation ovens, and API synthesis reactors where contamination of the product from the process equipment would have regulatory implications. The non-porous, chemically inert surface of fused silica is compatible with food-grade and pharmaceutical-grade hygiene requirements for components proximate to the product.
Environmental Monitoring & Gas Sampling
Industrial emissions monitoring systems and process gas analysers require sampling probes that extract representative gas samples from high-temperature flue gas ducts and process streams without altering the gas composition by condensation, chemical reaction, or adsorption on the probe surface. High-temperature quartz glass sampling probes are the preferred material for this application because fused silica does not catalyse reactions between sample gas components and does not adsorb the polar molecules and water vapour that cause measurement errors in metal or polymer sampling systems.
High-Temperature Quartz Glass: Frequently Asked Questions
Common questions from process engineers, furnace designers, industrial heating OEMs, and maintenance engineers sourcing high-temperature quartz glass components.
Yes. FGQuartz accepts custom high-temperature quartz glass orders from a single piece, with no minimum order quantity. Drawings in DXF, STEP, IGES, or PDF format are accepted. The engineering team provides Design for Manufacture feedback within 24 hours of receiving a drawing, and a detailed quotation — including unit price, lead time, and volume pricing — follows within the same business day for standard-complexity components. Custom fabrication routes available include CNC diamond machining, oxy-hydrogen flame forming and welding, precision grinding for flat sealing faces, and quartz-to-metal assembly for vacuum flange and feed-through configurations.
High-temperature quartz glass is used across industrial heating systems including infrared curing ovens and radiant heaters; metal heat treatment furnaces for annealing, sintering, and brazing; chemical processing reactors for CVD coating, catalytic testing, and gas-phase reactions; the automotive industry for paint and powder-coat curing; food processing for infrared surface treatment and pasteurisation; pharmaceutical manufacturing for depyrogenation and dry heat sterilisation; laboratory and scientific research for tube furnace reaction vessels; plasma processing systems for ICP analytical instruments and industrial plasma treatment; and environmental monitoring for high-temperature gas sampling probes.
Yes. Hydrogen is one of the most common atmospheres used in quartz tube furnaces for bright annealing of metals, reduction of metal oxides, and sintering of powder metallurgy components. Quartz glass does not react with hydrogen at typical tube furnace operating temperatures. Standard safety practice requires purging the tube with inert gas before introducing hydrogen and after completing the hydrogen atmosphere step, to prevent explosive hydrogen-air mixtures from forming during heating or cooling transitions.
Clear fused silica transmits infrared radiation efficiently, making it the correct choice for infrared quartz heater tubes — where the heating element must radiate energy through the quartz wall — and for observation windows that require optical access to the process zone. Opaque quartz contains microscopic voids that scatter and absorb radiation rather than transmitting it, giving it low thermal emissivity and effective thermal insulation properties. Opaque quartz is used for furnace liners, thermal baffles, and insulating spacers where heat retention is required rather than transparency. Many industrial heating systems use both grades together in the same assembly.
FGQuartz supplies quartz furnace tubes for industrial tube furnaces in clear and opaque grades; infrared quartz heater tubes for short-wave and medium-wave IR heating systems; thermocouple protection tubes in single and double-bore configurations with flame-sealed closed ends; high-temperature observation windows and sight glasses in circular and rectangular formats; opaque quartz furnace liners for thermal insulation between the process tube and furnace heating elements; electrical insulators, electrode isolation sleeves, and high-voltage feed-through assemblies; combustion chamber liners; and fully custom high-temperature quartz glass assemblies produced to customer drawings.
High-temperature quartz glass combines properties that no single alternative material can match at elevated temperatures: continuous service capability well above the limits of borosilicate glass, near-zero thermal expansion that resists thermal shock during rapid cycling, chemical resistance to most industrial process gases and acids at high temperatures, and UV-to-infrared optical transparency that allows infrared heaters to radiate through their quartz enclosures to the workpiece. No other affordable material simultaneously provides all of these properties across the full range of industrial thermal processing temperatures.