Duralox 997 Ceramic Pyrometry Tubes
Duralox stands for durable Aluminium Oxide and is a registered trade name of Jyoti Ceramic Industries Pvt. Ltd. It stands for Aluminium Oxide ceramic compositions content 90 to 99.7% & above percentage of Al2O3 in its residue.
Pyrometry Sheaths
The main feature of Duralox 997 Re-crystalized Alumina is its very high degree of chemical inertness, it offers a high degree of protection against reactive slags or furnace gasses and its low silica content ensures that there is no contamination of rare metals such as platinum by silicon a frequent cause of loss of calibration in thermocouples.
Tubes
Duralox 997 re-crystallized Alumina tubes pass good electrical resistivity as well as high thermal conductivity at high temperatures. When supported adequately, they can be used up to a temperature of 1800 0C + (3272 0F) and are suitable for molybdenum and tungsten wound tube furnaces, particularly for processes requiring a tube of an impervious nature.
Single and Multibore Insulators
Duralox 997 Re-crystallized Alumina can be used up to a temperature of 1800 0C. It is particularly suitable for use as an insulator for rare metal thermocouples, because of its extremely low silica content ; it ensures that there is no contamination of rare metals such as platinum with silicon. Duralox 997 alumina closed one end Ceramic Thermocouple Tubes are sintered vertically at approximately 1750 0C temperature, in oxygen atmosphere in microprocessor controlled bell type kiln. After sintering, 100% thermocouple tubes are tested under air pressure @ 4 bar to ensure gas tightness.
Duralox 997 Re-crystallized Alumina Ceramic is fine grained, non porous, dense and impervious to all acids except hydrofluoric acid. Duralox 997 is exceptionally high purity Alumina Ceramic, containing 99.7% Al2O3 and SiO2 less that 0.05% in its residue.
Physical Strength : Duralox 997 Alumina is extremely hard with high mechanical strength and resistant to abrasion & corrosion and good thermal conductor at high remperatures.
Imperviousness : Duralox 997 Alumina products are fired at extremely high temperature around 1750 0C which ensures impermeability under severe & critical conditions.
Good Electrical Resistivity : Duralox 997 Alumina maintains good electrical resistivity at high temperatures.
Ceramic tubes are cylindrical structures made from ceramic materials, renowned for their exceptional heat resistance, electrical insulation, and corrosion resistance properties. These tubes find widespread applications in various industries, including electronics, metallurgy, and aerospace. The inherent durability of ceramic tubes makes them ideal for use in high-temperature environments, where traditional materials might falter. The unique combination of thermal stability and electrical insulating capabilities positions ceramic tubes as crucial components in applications such as furnace heating elements, thermocouple protection, and insulating sleeves. As a versatile solution, ceramic tubes play a pivotal role in enhancing the performance and longevity of equipment across diverse industrial sectors.
High heat Conductivity : Duralox 997 Alumina products are considered as high-tech products and are manufactured with advanced technology, therefore maximum density is ensured with minimum wall thickness. This makes the highest possible heat transfer.
Stability at high temperature and chemical Inertness : Duralox 997 is inert even at high temperatures in reducing atmosphere and flux attack due to low silica content in its residue.
Product Range : Duralox 997 Alumina product range includes Ceramic thermocouple tubes with Closed One End (COE), Open Both Ends (OBE), tubes with Single and Multibores, Thin-wall tubes, Capillary tubes, Round and Oval rods above Ø 0.5 mm.
Amphoteric : Duralox 997 Alumina is highly resistant to acid slugs.
High temperature ceramic tubes are advanced engineering components designed to withstand extreme thermal conditions in various industrial applications. These tubes are crafted from durable ceramic materials known for their exceptional heat resistance, ensuring reliable performance in environments with elevated temperatures. Whether used in furnaces, kilns, or other high-temperature processes, these ceramic tubes provide excellent thermal insulation and stability. Their ability to maintain structural integrity under intense heat makes them indispensable in industries such as metallurgy, aerospace, and manufacturing. Engineered to endure harsh conditions, high temperature ceramic tubes play a crucial role in enhancing the efficiency and longevity of equipment operating in extreme heat environments.
Advantages :
Duralox 997 Re-crystallized Alumina Ceramic offers following advantages over the metals :
- Continuous high temperature resistance 17500C.
- Higher thermal stability.
- Lower thermal expansion.
- Inert to Hydrogen, Carbon and refractory metals under most server conditions, non-toxic, non-radioactive, non-magnetic and non-aging.
- Higher electrical insulation.
- Higher modules of elasticity, hence higher rigidity.
- Greater hardness and wear resistance.
- Higher abrasion corrosion and oxidation resistance.
- Higher compressive strength.
Typical properties of impervious Re-crystallized 997 Alumina ceramics
| Chemical Property | |
|---|---|
| Al2O3 | 99.7 |
| Alkali | 0.05% |
| Physical Property | |
|---|---|
| Colour | Ivory |
| Density | 3.85 – 3.90 g/cm3 |
| Porosity | Nil, Gas tight |
| Hardness on Vicker’s scale | 1550 / 1650 Hv5 |
| Hardness on Moh’s scale | 9 + |
| Flexural strength | 3000 Kg/cm2 |
| Young’s Modulus | 3.5 x 106 kg/cm2 |
| Co-efficient of linear thermal expansion (25 0C – 1000 0C) | 8 x 10-6 / 0C |
| Thermal Conductivity (25 0C) | 26 W/m0K |
| Max. working temp. in oxidizing atmosphere @ no load | 1800 + 0C |
| Dielectric strength (25 0C) (1.5 mm thick) | 25 Kv/mm |
| Volume Resistivity (25 0C) | 1014 Ω.cm |
| Thermal Shock resistance | Good 170 0C |
Chemical Characteristics of Duralox 997
In Vacuum
In Oxidising Atmosphere
In inert Atmosphere
| Reacts with thoria at about 19900C |
| Reacts with carbon at about 16500C |
| Reacts with magnesia at about 19000C |
| Reacts with zirconia at about 18000C |
| Reacts with beryllia at about 18600C |
| Reacts with magnesia at about 16000C |
| Reacts with zirconia at about 17000 C |
| Reacts with thoria at about 19000 C |
| No reaction with molybdenum at 18000C |
| No reaction with nickel at 18000 C |
| Slight reaction with niobium at 16000 C |
| Violent reaction with niobium at 18000 C |
| Slight reaction with titanium at 16000 C |
| Violent reaction with titanium at 18000 C |
| Slight reaction with beryllium at 18000 C |
| Slow reaction with silicon at 14000 C |
| Violent reaction with silicon at 16000 C |
| Slow reaction with zirconium at 16000 C |
| Violent reaction with zirconium at 18000 C |
Duralox 997 (DIN VDE 0335) RE-crystallized Alumina Ceramic Protection sheaths for Thermocouples & Sensors.
| Outer Dia (OD) | Inner Dia (ID) | Length Up to (L) | One Part (ISO pressed) |
|---|---|---|---|
| 6 | 4 | 1500 | - |
| 6.35 | 4.8 | 1500 | - |
| 7 | 5 | 213 | YES |
| 8 | 5 | 1500 | - |
| 9 | 6 | 1500 | - |
| 9.5 | 6.35 | 1500 | - |
| 10 | 6 | 1500 | - |
| 10 | 6 | 225 | YES |
| 12 | 8 | 1500 | - |
| 13 | 9 | 1500 | - |
| 15 | 6 | 1500 | - |
| 15 | 10 | 1500 | - |
| Outer Dia (OD) | Inner Dia (ID) | Length Up to (L) | One Part (ISO pressed) |
|---|---|---|---|
| 15 | 6 | 1030 | YES |
| 15 | 10 | 1030 | YES |
| 15 | 10.5 | 330 | YES |
| 17 | 13 | 1000 | YES |
| 17 | 13 | 1500 | - |
| 20 | 8 | 1000 | YES |
| 20 | 10 | 1000 | YES |
| 20 | 15 | 1000 | YES |
| 20 | 8 | 1500 | - |
| 20 | 10 | 1500 | - |
| 20 | 15 | 1500 | - |
| 24 | 18 | 100 | YES |
• Pyrometer protection sheaths (closed one end) are available from 100 to 1500 mm long.
Pyrometer Sheaths sizes not shown in above table can be made on request, if found feasible.
Only against specific enquiry, we can offer protection thermocouple sheaths and tubes with open both ends and with flanges, price on request. Please do not fail to specify length of the sheath in your purchase enquiry.
Workable dimensional tolerance are adhered to DIN standards 40680 medium class. Tubes with close tolerances can be manufactured on enquiry. Code RC PS corresponds to Re-crystallized Pyrometry Protection Sheaths. Sheath means closed one end Pyrometer tube.
ISO Pressed closed one end (COE) tubes with collar*
* Price on request.
Confirm collar dimensions, tube OD, tube ID and length.
Duralox 997 (DIN VDE0335) RE-crystallized Alumina Ceramic, Solid Round, Oval Rods, Single & Multibore Tube insulators (all dimensions are in mm)
| Solid Round Rods | Single Bore Tubes | 2 Bore Insulators | 4 Bore Insulators | Oval 2 Bore Insulators |
|---|---|---|---|---|
| Dm (Ø) | O Ø / I Ø | O Ø / B Ø | O Ø / B Ø | L / W x B Ø |
| 0.6 to 50 | 1 x 0.25 | 2.5 x 0.6 | 3 x 0.8 | 3 / 1.5 x 0.8 |
| - | 1.35 x 0.6 | 3 x 0.8 | 3.5 x 1 | 4.2 x 2.2 x 1.2 |
| - | 1.4 x 0.5 | 3 x 1 | 4 x 1 | - |
| - | 1.4 x 0.5 | 3 x 1 | 4 x 1 | - |
| - | 2.5 x 1.3 | 4 x 1 | 4.5 x 1.3 | - |
| - | 2.5 x 1.5 | 4.5 x 1 | 5 x 1.2 | - |
| - | 2.7 x 1.7 | 4.5 x 1.5 | 5 x 1.3 | - |
| - | 3.2 x 1.5 | 5 x 1.3 | 6 x 1.3 | - |
| - | 4.75 x 1.35 | 5 x 1.8 | 6 x 1.5 | - |
| - | 4.8 x 3 | 5.5 x 2 | 7 x 1.5 | - |
| - | 6 x 4 | 6.4 x 0.8 | 8 x 2.3 | - |
| - | 8 x 5 | 6 x 2 | 8.5 x 1.5 | - |
| - | 10 x 2.5 | 6.5 x 1.8 | 8.5 x 2.5 | - |
| - | 10 x 6 | 6.5 x 2 | 9.5 x 2.5 | - |
| - | 12 x 8 | 7 x 2 | 10 x 1.8 | - |
| - | 15 x 6 | 7 x 2.5 | 10 x 3.1 | - |
| - | 15 x 10 | - | 6.6 x 2 | - |
| - | 20 x 8 | - | - | - |
| - | 20 x 10 | - | - | - |
| - | 20 x 15 | - | - | - |
| * Ø = diameter in mm O Ø = outer diameter in mm B Ø = bore diameter in mm | ||||
Ceramic thermocouple tubes and Multibore tubes other than above sizes can be manufactured on request.
Duralox 997 single and multibore tubes and insulators are used for insulating thermocouple wires suitable for maximum temp 1800 0C according to DIN 43725 standards. Tube sizes other than as above shown in table can be made on request if found feasible. Dimensional tolerances are maintained to DIN 40680 medium class standards.
Dimensional tolerances and allowances are conforming to DIN standard 40680 medium class.
DIN standard 40680 Medium Class.For Diameters (OD-ID) – Length – Camber – Ovality and Eccentricity
| On diameter | Tolerances |
|---|---|
| 1 to 5 mm | ± 0.2 mm or 4% whichever is greater |
| 5.1 to 40 mm | ± 0.3 mm or 2 % whichever is greater |
| On Length | |
| 20 to 150 mm | ± 0.5 mm or 2% whichever is greater |
| 151 to 1500 mm | ± 2 mm or 1% whichever is greater |
| Allowance on Camber | 0.5% of the length |
| Allowance on Ovality | 0.1 mm or 0.5% of the diameter whichever is greater |
| Allowance on Bore eccentricity | 0.05 mm or 0.5% of the diameter |
Tolerances closer than above on request.
Duralox 997 Alumina Ceramic Thermocouple Tubes & Multibore tubes are formed by high pressure extrusion, dry/wet bag isostatic pressing.
We are constantly working for improvement of the product quality, hence the data given in the brochure may change as and when found necessary.
Information contained herein is to the best of our knowledge, true and accurate and is based upon measurements made in our R & D laboratory. Recommendations, suggestions and data are practical guidelines and not guarantees. Actual results may vary with conditions of use and with variations in the methods of manufacture, size and shape of the ceramic part. We disclaim any liability that may be incurred in connection with use of suggestions or data. This publications is not to be taken as licence to operate under or a recommendation to infringe any patents. Observation of all legal regulations and patents is the responsibility of the user.
