Applications / High Temperature
High Temperature Quartz
Fused silica for extreme thermal service
Furnace tubes, heating-element supports, kiln furniture, observation windows, thermocouple protection tubes and structural parts — produced from ≥ 99.99% SiO₂ for continuous operation to 1 200 °C, rapid thermal cycling and aggressive process atmospheres. Clear or opaque grade. Prototype from one piece. Engineering quote within 24 business hours.
Continuous
1 200 °C
Thermal expansion
5.5 × 10⁻⁷
Facility
ISO 9001
1 pc
Minimum custom prototype
40+
Countries supplied
Clear & opaque
IR transmit or insulate
15 000 m²
ISO 9001 plant, Lianyungang
Since 2005
Fused-silica specialist
Material
Why fused silica for continuous high temperature
Fused silica is one of the few practical materials that simultaneously delivers very low thermal expansion, high softening temperature, excellent thermal shock resistance and broad chemical inertness. Ordinary glasses soften or crack under loads that quartz absorbs without dimensional drift. Many engineering ceramics match temperature capability in isolation, but not the combination of shock resistance, electrical insulation, formability into tubes and complex shapes, and cost at industrial volume.
Continuous service to 1 200 °C, short-term peaks near 1 300 °C, and a softening point around 1 680 °C put fused silica well beyond borosilicate (~500 °C working limit) and most commercial optical glasses. The coefficient of thermal expansion — 5.5 × 10⁻⁷ /°C between 20 °C and 300 °C — is near enough to zero that rapid ramp cycles, door openings and local hot spots rarely fracture properly designed parts.
That combination is why high-temperature quartz appears in heat-treatment furnaces, process reactors, laboratory tube furnaces, kilns, semiconductor and solar thermal tools, vacuum systems and infrared heating assemblies — anywhere geometry must survive prolonged heat without contaminating the process or losing alignment.
1 200 °C
Continuous service
Far beyond borosilicate’s ~500 °C working limit. Short excursions to approximately 1 300 °C are common in process design. Softening point ≈ 1 680 °C provides margin for local hot spots and uneven loading.
Near-zero CTE
Thermal shock resistance
Coefficient of thermal expansion 5.5 × 10⁻⁷ /°C (20–300 °C). Survives rapid cycling, quench events and uneven heating that fracture borosilicate and many ceramics of similar geometry.
Products
High-temperature quartz components
Furnace tubes, element supports, kiln furniture, viewports, thermocouple protection tubes and fully custom assemblies — clear or opaque grade, drawn, CNC-machined or flame-worked to drawing. Geometry is selected for the thermal role; grade is selected for transmission versus insulation.
Process chambers
Furnace Tubes & Process Tubes
Clear and opaque fused silica tubes for horizontal and vertical high-temperature furnaces. Continuous service with thermal-shock resistance and dimensional stability under load. Ends can be plain, flanged, ground or flame-worked to match the furnace interface.
Use: Heat treatment · annealing · CVD · controlled atmosphere · vacuum
Element hardware
Heating Element Supports & Insulators
Quartz rods, plates and custom-machined supports that hold heating elements while remaining electrically insulating and thermally stable at temperature. Used where metal fixtures would short, oxidize or contaminate the process zone.
Forms: Rods · plates · CNC fixtures · isolation sleeves
Chamber furniture
Kiln Furniture & Structural Parts
Support plates, shelves, posts and custom fixtures used inside kilns and high-temperature chambers. Resistant to deformation and chemical attack under prolonged heat. Opaque grade is often preferred where insulation and low emissivity matter more than transparency.
Scope: Plates · posts · shelves · custom fixtures
Optical access
Observation Windows & Viewports
High-temperature quartz windows for visual or optical monitoring while maintaining hermetic sealing and thermal integrity. Circular and rectangular formats. Optical-grade clear fused silica for process observation, pyrometry access and IR transmission.
Grade: Optical-grade clear fused silica
Sensor protection
Thermocouple Protection Tubes
Closed-end and open-end quartz tubes that protect thermocouples in high-temperature and corrosive environments. Fast thermal response, chemical inertness and electrical insulation. Single-bore and double-bore configurations available.
Options: Single-bore · double-bore · flame-sealed ends
Built to print
Custom High-Temperature Assemblies
Flame-worked and CNC-machined components fabricated to customer drawings for specialized furnaces, reactors and thermal processing equipment. Multi-port tubes, closed assemblies, baffles and structural frames.
Input: DXF · STEP · IGES · dimensioned sketch · sample
Applications
Where continuous high-temperature quartz is specified
Industrial heat treatment, process reactors, laboratory tube furnaces, kilns, semiconductor and solar thermal equipment, vacuum and controlled-atmosphere systems, and infrared heating assemblies all rely on the same core properties — only geometry, grade and duty cycle change.
When the process atmosphere is oxidizing, inert or mildly reducing, and when metallic contamination must be avoided, fused silica is usually preferred over metal or lower-purity ceramics for the hot-zone hardware.
- Industrial heat-treatment and annealing furnaces — process tubes, liners and supports under continuous thermal load
- High-temperature process reactors and CVD systems — chamber tubes and gas-handling quartzware
- Laboratory tube furnaces and research equipment — standard and custom tubes for R&D and pilot lines
- Ceramic and glass manufacturing kilns — furniture, posts, plates and insulating components
- Semiconductor and solar thermal processing — furnace tubes, liners and related high-temperature hardware
- Vacuum and controlled-atmosphere furnaces — hermetic windows, tubes and structural parts
- Heating-element assemblies — electrically insulating supports and isolation sleeves
- Infrared curing, depyrogenation and dry-heat sterilisation — clear IR-transmitting tubes and windows
Clear vs opaque
Transmit or insulate — grade selection
Clear fused silica transmits infrared radiation efficiently. Opaque fused silica contains microscopic closed voids that scatter and absorb radiation, lowering emissivity and acting as a thermal insulator. Many industrial systems use both grades in the same assembly — clear where optical or radiative access is required, opaque where heat retention and shielding matter.
Choosing the wrong grade produces the opposite of the intended thermal behaviour: a clear tube where an opaque liner is needed allows heat to escape; an opaque window where optical access is needed blocks pyrometry and visual inspection entirely.
Clear fused silica
IR transmission · optical access
Infrared heater tubes, observation windows, process zones that must radiate or be inspected, pyrometry access and UV/IR optical paths through the hot zone.
Opaque fused silica
Insulation · heat retention
Furnace liners, thermal baffles, insulating spacers and furniture where heat retention is required rather than transparency. Lower thermal emissivity helps stabilise the process zone.
Key material advantages
Typical values for high-purity fused silica used in continuous high-temperature service. Exact performance depends on geometry, grade, atmosphere and thermal history.
Continuous service temperature1 200 °C
Short-term maximum1 300 °C
Softening point≈ 1 680 °C
Thermal expansion (20–300 °C)5.5 × 10⁻⁷ /°C
SiO₂ purity≥ 99.99 %
Thermal shock resistanceExcellent
Chemical resistance (most atmospheres)Outstanding
Electrical insulation at temperatureYes
Grades availableClear & opaque
Atmospheres & design
What to specify on the RFQ
Service life and reliability depend on more than temperature alone. Atmosphere chemistry, ramp rates, mechanical load, contact materials and cleaning practice all influence how long a quartz component lasts in the field.
Fused silica performs well in air, inert gases, vacuum and many mildly reducing atmospheres. Strongly reducing conditions, alkali vapours and certain fluorine-containing chemistries can attack the surface and should be flagged early. Mechanical design should avoid point loads and sharp stress concentrators; annealing after flame working reduces residual stress from fabrication.
When you request a quote, include maximum continuous temperature, peak temperature if different, atmosphere composition, required dimensions or a drawing, clear versus opaque preference, and any sealing or optical requirements. That information is usually enough for a first engineering recommendation and a firm quotation.
Fabrication
Drawn, CNC-machined and flame-worked under one roof
Vertically integrated at 15 000 m² in Lianyungang: tube and rod drawing, oxy-hydrogen flame working, multi-axis CNC, fire polish and annealing under ISO 9001. The same facility supplies semiconductor, solar, optical and laboratory quartz — so mixed orders and matched thermal-process sets can be coordinated from a single quality system.
DXF, STEP or IGES preferred; a dimensioned sketch or a photo of a sample is often enough for a first assessment. One-piece prototypes are accepted. After drawing approval, typical lead times run 3–6 weeks depending on complexity and load.
01
Precision tube & rod production
High-purity fused silica tubes and rods drawn to controlled dimensions for furnace chambers, supports and protection tubes.
02
CNC diamond machining
Custom supports, plates, fixtures and complex geometries machined from solid fused silica stock to tight tolerances.
03
Oxy-hydrogen flame forming
Flanged tubes, closed-end protection tubes, multi-port assemblies and special shapes — annealed for stress relief under thermal cycling.
04
Fire polish, anneal, inspect
Stress-relief annealing, dimensional metrology and optical defect inspection. Certificate of conformance available on request.
FAQ
Questions process and procurement actually ask
Custom capability, atmospheres, clear versus opaque selection, maximum temperature and product scope. If the answer is not here, put it on the RFQ — temperature, atmosphere and a drawing or sketch are the minimum useful inputs.
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.
RFQ
Source high-temperature quartz for your process
Tell us maximum continuous operating temperature, peak temperature if different, process atmosphere, required dimensions and functional requirements (tube, support, window, protection tube or custom assembly). DXF, STEP, IGES, a dimensioned sketch or a photo of a sample are enough to start. Prototype quantity: one piece.
- Quote within 24 business hours
- File formats: DXF, STEP, IGES, PDF
- Clear and opaque grades
- Typical lead time 3–6 weeks after drawing approval
- Prototype through OEM volume