The production and consumption of tantalum and its compounds are mainly concentrated in the China, Japan, Western Europe and other countries. The industrial raw materials for the production of tantalum include natural concentrates, artificial concentrates and tantalum-containing tin smelting slag. The main commodities used in the tantalum processing industry are tantalum carbide, tantalum oxide, K2TaF7 and metallic tantalum or tantalum alloys
Unprocessed tantalum powder is obtained by sodium reduction or electron beam smelting, and then special grade tantalum is obtained through hydrogenation and dehydrogenation processes, and then processed into various products such as foil, plate, wire, etc. The annual consumption of tantalum in the form of metallic tantalum or compounds is more than 900 tons. Tantalum has four main applications: capacitor alloys, cemented carbide, and chemical equipment and industrial instruments. In the past 25 years, the demand for tantalum has fluctuated greatly. In the next 10 years, the annual consumption of tantalum will be about 950 tons to 1150 tons, and the focus will shift to the production of high-tech metals.
1. Capacitors
Since tantalum used in capacitors accounts for a considerable percentage of the total consumption (45% in 1986), the future market of the capacitor market basically determines the future development of the tantalum industry. At present, tantalum capacitors account for about 4% of the total capacitor market. Tantalum oxide has a high dielectric constant and good stability. Tantalum powder, tantalum wire and tantalum film can be used to make capacitors. Tantalum capacitors are characterized by high stability, low leakage rate, small size and high capacitance, and stable working performance between -60℃ and +200℃. Tantalum capacitors compete with aluminum electrolytic capacitors and multilayer ceramic capacitors for development.
Despite competition with other types of capacitors, and due to the development of tantalum powder with particularly large specific capacitance (22000μFV/g), the miniaturization of tantalum capacitors and the reduction of tantalum consumption per capacitor, the total consumption of tantalum used to manufacture tantalum capacitors is still increasing, and the corresponding demand for tantalum capacitors is increasing.
2. Chemical and instrument manufacturing industry
The good corrosion resistance of tantalum oxide film makes tantalum widely used in chemical engineering. In 1986, the chemical industry consumed 15% of tantalum production. Tantalum components are used to be installed in corrosive equipment, such as heat exchangers, spark plugs, coolers, pipelines, container coatings, etc. Despite its high price, tantalum is still developing in fierce competition with special steel, lead, glass, ceramics, enamel and plastic coatings due to its excellent durability and reliability. Although the initial investment cost of various tantalum equipment is very high, on the other hand, its maintenance and repair costs are low, and the equipment life is quite long.
Tantalum is also used as the emitter of various gas purification devices, and can also be used as the positive electrode of electron tubes and centrifugal ejectors. The electronics industry uses tantalum to make transmitting tubes and various heavy-load components. Tantalum has a high melting point and a low probability of recrystallization, so it can be used as a thermal conductor material and a coating process for high-temperature vacuum technology. Human cell tissue can withstand metallic tantalum, so tantalum can be used in surgical medicine to make artificial bones or various human joints.
3. Alloys
Non-alloy tantalum used directly in industry is very limited. This is because of its relatively low thermal strength and weak oxidation resistance in high-temperature air. In 1986, only 10% of tantalum was consumed in the alloy industry. The most commonly used tantalum alloys are Ta-W and Ta-W-HF. These alloys are used to make high-temperature resistant parts in space shuttles and engines. The addition of tungsten also improves the corrosion resistance of tantalum to hydrofluoric acid.
The amount of tantalum consumed in superalloys has increased significantly. It can improve the corrosion resistance of nickel-based, cobalt-based, and iron-nickel-based alloys, making their grain structure finer, stable to carbon, and increasing hardness and tensile strength. Tantalum-containing superalloys are more expensive than alloys without tantalum, but they have a longer life and are more corrosion resistant. Superalloys are mainly used in aviation, propulsion, jet engine technology, and aerospace engineering and nuclear power engineering.
In the steel industry, iron-tantalum alloys have been largely replaced by iron-niobium alloys because iron-niobium alloys are cheaper and more effective.
4. Cemented Carbide
The cemented carbide industry is the second largest user of metallic tantalum. The consumption of tantalum in cemented carbide accounts for 30% of the total tantalum production. The cemented carbide industry uses tantalum as TaC or mixed carbides (Ta, Nb)C, (W, Ti, Ta) C and (W, Ti, Ta, Nb)C cemented carbides [17]. Various tantalum carbide additives improve the corrosion resistance, hot strength, hardness, ultimate bending strength, toughness, impact resistance and grain refinement of cemented carbides. The high price of tantalum, especially the price increase from 1979 to 1980, led to the use of mixed carbides, mainly (Ta, Nb) C containing 30% Nb, to replace TaC. Mixed carbides are cheaper than pure TaC and have similar properties to TaC. However, the production of these cemented carbides requires careful control of sintering conditions. Only 15 years ago, TaC accounted for 10% of cemented carbides, but now it is only 2.3% (19). Pure cemented carbides with TiC as the main component (such as TiC-NiMo) and cutting tool cemented carbides inlaid with cemented carbides (such as TiC, TiN, TiCN and Al2O2) are gradually becoming competing products. The increasing use of cemented carbide products and the increase in tantalum substitutes are roughly offset, so it is expected that the consumption of tantalum will not change much in the next few years.