Tungsten mesh heater- A largely used material for furnaces

Tungsten mesh is a recommended material for use as a furnace heating component. By virtue of its outstanding properties, tungsten mesh withstands multiple heat cycles without degradation hence providing long service life. A large surface area provides good watt density and resistance can be adjusted to increase efficiency.

Tungsten is known to be easily oxidized even at moderate temperatures. Tungsten basis heater brings the revolutionary performance. Offering comfort over traditional portable heater while fueled by same gas cylinder, the tungsten basis heater provides directional and evenly heating in an effective and efficient manner.

Tungstenmesh’s unique properties maximize the heater performance while providing superior heat distribution. Tungsten mesh screen provides significant wind resistance when combined with double thermocouples, providing suitable service in winds running at speed of 12 km/h.

High temperature heating Tungsten mesh known for its high melting temperature is widely used in manufacturing high temperature furnaces, heating elements and insulation screens. Tungsten heating mesh can be used up to 2800oC or 5070oF in vacuum.

How to choose a furnace heating element

The commonly used materials for furnace manufacture are tungsten, molybdenum and tantalum. These metals are also widely used as racks, skids and boats for material processing for example sintering, annealing and vacuum brazing. Advantages of refractory metals comprise good electrical properties, low vapor pressure, low electrical resistivity and nominal heat capacity. A crucial property of a refractory metal is low thermal capacity. A furnace heating element with low heat capacity quickly heats up and cools down. Energy savings are ensured because heat does not waste during heating the materials.

Tungsten also provides outstanding resistance to molten glass hence is fit for use with dies and mandrels and as electrodes in the melting operations. While choosing a refractory metals for furnace applications, service conditions and properties of the product under processing is also considered. Tungsten is the most commonly used refractory metal in furnace conditions. The refractory metals are readily fabricated by traditional methods but tungsten is difficult to fabricate. It has major applications in high temperature applications up to 2800oC in inert or protective and reducing conditions. At such high temperatures, it is challenging to insulate the hot region. It is common to use tungsten in a vacuum or low partial pressure condition.

Tungsten mesh in the finished form inherits the properties of tungsten providing outstanding heat resistance and electrical resistivity. It is widely used for radiation shielding and as a heating element for vacuum furnace. For its outstanding corrosion resistance, it is used as filter or sieve material for service in acid and alkali environments.

Major application fields of Tungsten mesh include: acid production, filtration, heat shielding, electronics, battery, vacuum equipments, chemical plants and science research labs. Tungsten mesh when used in heaters is formed and welded. It is highly durable and can withstand higher temperature above 2000oC. For its excellent properties, Tungsten mesh is largely used in the construction and design of components for high temperature furnaces. Tungsten mesh heater provides high performance radiant heating to outdoor and semi-enclosed areas. Its high temperature performance makes it usable in all conditions.

Use of Nickel based super alloys for heat pipes

There are various applications that use heat pipes in the moderate temperatures of 450K to 750K such as space nuclear power system radiators, fuel cells, geothermal power, waste heat recovery units and high temperature electronics cooling. Various life tests have been conducted at temperatures of 673K using Hastelloy B3, C22 and Hastelloy C2000, Monel 400 and Monel K500. The test fluids are evaluated and regions of the heat pipes are analyzed to determine the magnitude and type of corrosion in the heat pipes. It is found that Monel heat pipes are suitable for service up to 550K. Copper depleted zones and copper surface nodules developed on the Monel 400 screen wick however not on the Monel K500. Hastelloy B3, C22 and C2000 at 673K were suitable. Alloy C2000 received nominal corrosion when used with titanium tetrachloride. On the other hand, Hastelloy C22 attained 5 to 10 micro-m thick double corrosion layer when evaluated with AlBr3 service fluid. The outcomes show that the tested envelope materials and service fluids can develop feasible material- service fluid combinations.

There is no commonly accepted service fluid over the whole intermediate temperature zone. Likely service fluids comprise elemental working fluids like sulfur, organic compounds and halides. Intermediate temperature based heat pipe life analyses were conducted for 40 years to find suitable working fluid and envelope combinations.

Monel water heat pipes

Various water working fluid heat pipes made from Monel K500 and Monel 400 are tested at different temperatures for different durations. While Monel 400 heat pipes offered suitable service, there were also some surprises found with these tests. Wide changes such as the development of dark subsurface layer and bright nodules were found in the alloy. Although the variation was the most extensive for the Monel- water heat pipes, Monel 400 wire mesh’s morphology was also typical. On the other hand, Monel K500 does not show wide change. Close test of the envelope exhibits a nominal corrosion. Inclusion of various elements to Monel K500 seemed to stabilize the alpha phase and inhibit this degradation. While no large magnitudes of oxygen were noticed, preferential oxidation of Nickel may also have played significant role in the development of the observed morphology and phases. Both Monel 400 and K500 are widely used in steam plants.

Hastelloy C alloys for heat pipes

Hastelloy C2000 and C22 are used with TiCl4, AlBr3, SnCl4 and other heating fluids. Alloy C2000 made a wide reaction with SnCl4. On the other hand, Hastelloy C22 provided significant performance in the heating fluid media and took a considerably long time to build up the corrosion layers.

Hence these Nickel based alloys are found to be suitable for the heating pipe materials for providing outstanding performance in the vigorous conditions. They prevent corrosion in the significantly long time and found to be consistent with the working fluids.

High corrosion resistant materials for fluorine based applications

Fluorine is the strongest oxidizing agent among all chemical elements. It is used in large magnitudes on an industrial and lab scale in atomic energy sector. Fluorine also develops the most stable metal fluoride layers. In alloy selection, the diffusing element in the alloy must develop only single and nonvolatile fluoride. Different metals provide different levels of corrosion resistance. Nickel offers the best corrosion resistance while the steel provides nominal performance.

Suitable choice of materials of construction is important for the safe operation of any system or piece of equipment. The common metallic materials of construction for use with fluorine near room temperature or below about 250oF are steel, Monel, nickel and aluminum. These materials develop thin, protective corrosive layers and are more corrosion resistant as compare to others. Iron and steel are the common commercial storage container materials: Monel and Nickel provide the best performance as systems, tubing and are preferred for high temperature operations. Copper tubes are useful in various applications, particularly near room temperature, although with increase, its reactivity more increases as compare to Monel and Inconel.

In alloy selection, the diffusing elements in an alloy should develop only single stable and nonvolatile fluoride. Using nickel based alloys, the fluoride layer developed is NiF2. The chosen alloy should be single phase because in multiple phase alloys, one phase is attacked at a higher rate and it rapidly attains intergraular corrosion and stress corrosion cracking. One phase should be leached out fully. Alloys may become incompatible at lower temperatures as compare to resistant basic metal. Intermetallic compounds are attacked faster as compare to pure component.

While using less resistant materials, it is recommended to plate the metal with a resistant metal. Use of electroplated nickel is best. On the other hand, while using Monel400 for fluorine based processes, the layer formed is a mixed fluoride of the major alloy compositions of approximately the composition of the alloy. For nickel 200, the fluoride layer is fluoride of the main element.

Metals for Fluorine based rocket fuels

In aerospace applications where propellants considered for storage in space at temperatures below -200oF include fuels like oxygen difluoride, fluorine-oxygen mixtures and chlorine trifluoride. The recommended metals and alloys for use for this application are aluminum, nickel, copper, titanium and stainless steels. These materials are found suitable for construction of equipments for storage and handling the semicryogenic propellants for duration of two to ten years. These high functional materials are found to provide suitable physical properties at extremely low temperatures, resist corrosion and corrosion as well as not to induce propellant decay.

Corrosion rates of Nickel based alloys are very low in fluorine based solutions and environments. Therefore these alloys are recommended for use in these applications. These materials are sturdy, durable and corrosion resistant that they can withstand fluorine based conditions at various temperatures for long period. So contact Heanjia Super-Metals for finding more information about these materials and choosing a suitable one.

Decorative Wire Mesh- Elegance to homes, gardens and offices

Decorative Wire Mesh is produced in various designs and textures. It provides elegance to walls and ceilings by producing an excellent textural appeal. It is used to produce beautiful architectural elements when installed on facades of buildings. Woven Wire Mesh has applications in various residential and commercial applications including signs, railing infills and plant screens. Room dividers are produced using Metal mesh products for installation on a retractable attachment or movable track. Mesh products are used in Sun screens, Texture & Space mesh, Decorative ceilings and wall mesh. Decorative Wire Mesh gives a beautiful look to homes and businesses. The customized panels of perforated metal mesh provide a great aesthetic appeal to various applications including desk fronts, water fountains, elevator panels and walls.

There are various designs available for Metal Mesh screens. Wire Mesh panels and fabrics are produced in a variety of types to complement different designs. The architectural mesh fasteners are versatile and durable. These are produced in a wide range of designs. Decorative Wire Mesh is used to provide elegance and originality to various types of architectural projects. The perforated metal mesh and fabrics are manufactured in a variety of designs to fulfill various types of requirements.

Woven Wire Mesh is a versatile product manufactured for use as Security Mesh, Concrete Reinforcement and Architectural Sculptures. Woven Wire Mesh can filter even the smallest particles. Stainless steel wire mesh is commonly used as it is economical. Decorative Wire Mesh is produced with various types of alloys and metals. Woven Wire Mesh is weaved in different styles including plain weave which is made with every wire going over and under every other wire and twilled weave that is made with the wires crossing two over and two under. Woven Wire Mesh is also weaved in a variety of Dutch styles.

Flattened Expanded Metal Mesh is a smooth surface with diamond-shaped openings used for various applications including security, machine guarding and equipment enclosures. Stainless steel has high resistance to corrosion and oxidation. Stainless steel is used in security screens, landscaping, shading, lighting diffusers and ceiling panels as it gives an aesthetic appearance along with excellent mechanical properties.

Nickel is another metal which is used for manufacturing Decorative Wire Mesh. It is expanded metal material that has high formability and ductility. It oxidizes at room temperature at a slow speed and has excellent thermal, magnetic and electrical properties.

Expanded Stainless Steel Mesh has a long life and is economical. It has good strength and is highly decorative. Expanded Stainless Steel metal mesh is available in various shapes including round, hexagonal, square and diamond produced from slit and stretched sheet metal. 

Decorative metal mesh expanded Stainless Steel has resistance to heat and corrosion in various environments. The original material is rigid and the annealing of the mesh is performed to achieve high formability. Expanded Stainless Steel Mesh has various uses due to its durability and is used in various industries such as filtration, food service, acoustics, HVAC services, petrochemical, architecture and automotive.

Sintered Mesh- Excellent filtration for high pressure applications

The characteristics of woven wire mesh are improved by bonding the contact points of all the wires together to form a mesh whose wires are securely fused in place and this process is known as Sintering. This is obtained using a combination of heat and pressure and the result is a single layer Sintered Wire Mesh. 5-Layer Sintered Wire Mesh is one of the most common types of Sintered Wire Mesh laminates and it is widely used. A single layer of fine woven wire mesh is placed between two layers of coarser square woven meshes and then added to two layers of a strong Dutch woven wire mesh and sintered together to form a  strong plate. 

The single layer of fine woven wire mesh acts as the filtration layer and can be customized to meet a particular filtration rating ranging from 1 micron to 200 microns. These layers consist of 316L stainless steel wire mesh. Other alloys can also be used including Inconel, Hastelloy and Monel. Standard size is a 2’x4′ or 4’x4′ sheet and various size tubes, cones, discs and larger sheets can be fabricated. This Sintered Wire Mesh laminate is used in numerous industries including food & beverage, pharmaceuticals, transportation and chemical processing. Various applications of this Sintered Wire Mesh laminate include pharmaceutical powder processing, fluidized beds, liquid and gas filtration.

PerforatedMetal Sintered Wire Mesh is a laminate made by taking several layers of woven wire mesh and sintering them to a layer of perforated metal. The woven wire mesh layers consist of a filter layer, a protective layer and possibly a buffer layer between the fine mesh layer and the perforated plate. The perforated plate is then added as the base and sintering is performed on the entire structure to form a strong and tractable plate. This Sintered Wire Mesh laminate has high resistance to pressure and has high mechanical strength due to the support of the perforated plate. It is ideal for various applications that require filtration and also require the protection and preservation of the filtration layer. One such application is oil wells where fine particles need to be filtered under extremely high pressure conditions. Various alloys can be used including the 316L stainless steel wire mesh which is commonly used for the woven wire mesh layers and the 304 stainless steel which is commonly used for the perforated plate. 

The customization of the woven wire mesh layers can be done to meet the filtration rating and the customization of the thickness of the perforated plate and type of perforations can also be done. Standard size is 2’x4′, or 4’x4′ and various size discs and sheets can be manufactured. This Sintered Mesh Laminate is commonly used in tube form. The customization of these sintered filter tubes is done in a variety of diameters and lengths.

Another type of Sintered Wire Mesh laminate is Plain Weave Sintered Square Woven Wire Mesh that is manufactured by sintering multiple layers of plain weave square woven wire mesh together. This Sintered Wire Mesh laminate has excellent permeability characteristics and low resistance to flow due to the large open area percentages of the square woven wire mesh layers.

Tungsten Mesh- Ideal material for electrodes

Uniformshaped Tungsten Meshes are used as screen or gauze. These are produced in standard metal mesh size range from 0.75mm to 1mm to 2mm diameter with strict tolerances and alpha values (conductive resistance) for uses such as gas detection and thermometry tolerances. Materials are produced using solid state, crystallization and other ultra high purification processes such as sublimation. Custom compositions are also produced for commercial and research applications and for new proprietary technologies.

Tungsten metal has a lustrous and silvery white color and doesn’t occur naturally. It is found in the ore Wolframite which is a tungstate of iron and manganese. It is converted to the trioxide and then reduced to the metal by reduction in hydrogen. Tungsten metal is relatively inert and has resistance to acids and alkalis. It has resistance to attack by oxygen although it reacts with fused oxidizing alkali media. It has high melting point and can be worked with relative ease when pure. Tungsten can be extremely brittle due to the presence of impurities and becomes difficult to fabricate. Tungsten is ideal for use as electric filaments due to its high melting point. Tungsten and its alloys are used in military applications for example, shells and armour, as well as counter-balance materials. Tungsten carbide powder with possible additions of titanium and tantalum carbides along with nickel or cobalt powders are compressed and sintered to produce cemented carbides. These cemented carbides are used to form the tip of cutting and drilling tools or for parts which will be subjected to heavy usage.

Tungsten is used in electrodes, electronic applications, medical devices and vacuum heating elements due to its high melting point and tensile strength at extreme temperatures. Tungsten and Molybdenum elements are produced in both mesh and weave configurations. The mesh and weave heating elements are made from continuous interlocked tungsten or molybdenum wire coils. Each wire moves independently when heated. Interlocked wire coils mean that each element has built-in flexibility. This largely eliminates mechanical and thermal stresses leading to improvement in the life of the element. These elements are manufactured in cylindrical and flat panel designs. Mesh elements consist of individual helix coils of tungsten or molybdenum wire that are threaded together by turning each coil into the adjacent coil making a continuous interlocking mesh pattern over the entire width and length of the element resulting in unmatched thermal performance. Consistency is maintained throughout the construction of each element since the wire diameter for each coil is closely controlled. Conductors are made of the top and bottom ends which are secured with solid strips of tungsten or molybdenum bands. These conductors provide a means of mechanical support for the element. The welding of these bands and tabs is performed under a controlled atmosphere to minimize stresses within the elements.

Individual wires are formed into planar sinuous loops to produce weave elements. The wire diameter, height and pitch of the bends are controlled as required to produce the optimum weave element design. A hair-pin wire is connected together with the individual wires passing through alternating loops similar to a cloth fabric weave to securely lock the wires together. The individual wires are free to move and adapt to the thermal environment. The weave is an alternative to the mesh construction technique. The ends are terminated in the same way as the mesh elements.

Inconel 718 Wire- Excellent material for use in springs

Inconel 718 is an alloy of nickel and chromium with excellent resistance to postweld cracking. This alloy has high creep-rupture strength at high temperatures to about 1300°F and it is age-hardenable. It is readily fabricated into complex parts and can be cold rolled to achieve the temper properties. Two types of heat treatments are utilized for Inconel 718. One is the solution anneal at 1700-1850°F followed by rapid cooling in water and precipitation hardening at 1325°F for 8 hours, furnace cool to 1150°F, hold at 1150°F for a total aging time of 18 hours followed by air cooling. Another is solution anneal at 1900-1950°F followed by rapid cooling in water and precipitation hardening at 1400°F for 10 hours, furnace cool to 1200°F, hold at 1200°F for a total aging time of 20 hours followed by air cooling.

Inconel 718 has its applications in

·        Seal rings

·        Gas turbine components

·        Nuclear hold down spring and other components

·        Springs

Springs are manufactured for use in environments with high or low temperatures and aggressive conditions in applications including

·        Space and aircraft industry

·        Oil and gas exploitation

·        Chemical processes

·        Heating processes

·        Power production

·        Petrochemical industry

·        Marine environments

Inconel 718 is used to produce various types of springs such as Disc springs, Compression springs, Torsion springs, Leaf springs and Tension springs. Inconel 718 has high strength and high corrosion resistance for use from -250°C to 700°C. It is used in applications including liquid fueled rockets components, sheet metal parts for turbine engines & fasteners and rings. It needs ageing treatment to develop best spring properties for spring applications.

Leaf springs and coil springs are widely used in the motor vehicle industry. Premature fatigue failure is common and the reasons for these failures are complex such as heat treatment, intergranular cracking, grain boundary embrittlement, design deficiencies, steel alloy chemistry and presence of Fe-S inclusions. This study provides an overview of spring steel including its heat treatment, fatigue failure, chemistry, residual stress and failure analysis of leaf and coil springs.

A spring is a component that can store energy temporarily and permanently. There is a need of improving fatigue strength of spring materials due to cyclic loading that accompanies the use of springs. Spring efficiency is related to its ability to store energy per unit weight and steel strengths of greater than 1379 MPa are required. Spring steels were developed to meet ever-increasing demands for improved mechanical properties with lower weight suspension materials to facilitate the larger effort of developing automotive vehicles with lower weights and lower cost. High strength spring steels with improved sag strength, fatigue strength and improved quench embrittlement properties in addition to other thermophysical and mechanical properties were developed in this work. 

The two types of springs were discussed such as helical coil springs and leaf springs. Coil springs are commonly used in the automotive industry and are constructed from a length of round steel wire that is formed into loops which allow for movement. Coil springs are classified as compression and extension springs. The objective of this study was to provide an overview of the most important factors involved in either coil spring or leaf spring failures. As per the conclusion of this study, surface defects including decarburization but the presence of seams, laps and other defects lead to premature spring failure. High quality outer layer of spring wire is achieved by a grinding or a draw-peeling process to address these problems. Emphasis on spring design innovations is increased which can be used with higher loads at reduced spring weight and size with substantial improvements in fatigue strength.