Titanium and its alloys have outstanding performance such as low density and corrosion-resistant, high temperature resistant, etc. world's titanium industry is undergoing a major market for the aerospace a single model, to metallurgy, energy, transportation, chemical, bio-medicine and other civilian areas which focus on the development of multi-mode transition. At present the world's titanium production in the industrialized countries only are the United States, Japan, Russia, China and such small number of countries, and the world's titanium production is only tens of thousands of tons per year. However, due to the significant strategic value of titanium and status in the national economy, titanium will become "third metal," after the rise of iron titanium, aluminum. The 21st century will be the century of titanium.
The current methods of production of titanium is metal reduction method, which refers to the use of metal reducing agent (R) with the metal oxide or chloride (MX) preparation of metal M. Titanium metallurgy magnesium thermal reduction (Kroll) and sodium reduction method (Hunter method)has been achieved in industrial production. Only the method of method was widely used in industry at present because Hunter Fabian Kroll costs are higher than Kroll method. Kroll method was criticized ever since its exploration in 1948 because of its high cost and low reduction efficiency .Half a century has passed, the process has not fundamentally changed, remains intermittent production, failed to achieve continuous production.
New trends of titanium production methods
After decades of development of world’s titanium industry, although a series of improvements have been made in Kroll and Hunter methods, yet they are still intermittent operation, the improvement of small and not significant reduction in the price of titanium. And should therefore be the development of new, low-cost continuous process in order to fundamentally solve the problem of high production costs. Therefore, the researchers conducted a large number of experiments and research. The focus of current research has the following methods: the electrochemical reduction method in order to reduce costs, direct oxygen titanium were studied. Abroad was the method of electrochemical solid titanium to reduce the concentration of dissolved oxygen to the limits of detection (500 ppm) below. In their view, the electrochemical process of oxygen, the oxygen dose of calcium chloride in the molten salt electrolysis generated, O2-at the anode to formCOorCO2precipitation. This new high-purification method, not only for the deoxidation of titanium, but also applies to Y, Nd and other rare earth metals, and can reduce the oxygen content to 10ppm.
The industrialization experiment process of electrochemical methods is this : first, titanium dioxide powder by pouring or pressure forming, sintering after the cathode, graphite as the anode in order to the molten CaCl2, graphite or titanium in the crucible in electrolysis. The voltage 2.8V ~ 3.2V, less than the decomposition of CaCl2 voltage (3.2V ~ 3.3V). After a certain period of electrolysis, cathode ?change from white to gray, observed under SEM, 0.25μm into TiO2titanium sponge 12μm. take chloride as molten salt, the most important reason is its low price, and O2 has a certain solubility, so that precipitation can not easily be oxidized titanium; In addition, CaCl2 non-toxic, non-polluting to the environment.
compared with TiCl4 molten salt electrolysis, raw materials used in this method is oxid rather than the volatile oxides of chlorine, so the preparation process can be simplified, and product quality is high; price of titanium ions in the redox reaction will not happen; anode precipitation pure oxygen gas (inert anode) or CO, CO2 mixed gases (graphite anode), easy to control, non-polluting.
The law not only advanced the vicinity of cathode reduction reaction, but can get reduction of titanium deoxidation at the same time. This approach direct electrolytic reduction of oxides and electrochemical deoxidation method, is the preparation of a new method of titanium, titanium extraction process to become the most eye-catching way. According to British journal Naturein 2000 paper to estimate the data using this method, per tone of titanium sponge to reduce the cost of production of about 13,000 U.S. dollars, the current 50 thousand tons of global output if the production by the electrochemical method, the annual savings of 770 million U.S. million of production costs.
Armstrong Law Hunter method was improved by Amstrong, etc.making continuous production process. The process is: first TiCl4 gas injection of molten sodium excess, excess sodium from the cooling of the product to restore and bring the product into the role of the separation process. Remove sodium and salt can obtain titanium powder products. Products, the minimum oxygen content of 0.2% to the standard Titanium 2. Slightly on the process improvements, can produce VTi, AlTi alloy. Compared with Hunter method, the method of continuous production with less investment and a wide range of product applications, by-product is decomposed into sodium and chlorine to the merits of recycling.
The method has been closing to industrial production, but there still exist several problems, such as how to further low oxygen content, what’s products’ costs, etc.
Stand on electroanalysis technical process sides, TiCl4 electrolytic electrolytic reduction process, the application of TiCl4 electrolysis is superior than both Kroll and Hunter methods. Therefore, the development of heat from the Kroll reduction, there was the smelting process of titanium into the idea of electrolysis.
TiCl4 electrolytic reduction method is the only technical method has been regarded as a possible way to replace Kroll process, the United States, the former Soviet Union, Japan, France, Italy, China ,etc. have done long-term and in-depth study. Electrolytic reduction method using TiCl4 technically TiCl4 need to change the first bit of the low-cost titanium chloride and dissolved so that the melt at the same time, the district must be the cathode and anode zones separated and sealed electrolyzer.
Italy has someone committed to the study of TiCl4 electrolysis through electrolysis of chloride analysis of the data and found that when the temperature is above 900 ℃, there is no electrolyte Ti2＋ or Ti3＋, only the Ti4 + and Ti. Established the basis for the electrolysis process for: TiCl4 gas injection and multi-layer electrolyte absorption. This multi-phase formed by potassium, calcium, titanium, chlorine, fluorine ions, as well as potassium, calcium, and that the titanium and graphite anode separated from cathode. Generation at the lowermost stratum of liquid titanium at the bottom to sink into the pool with a water-cooled copper crucible, the ingot form. However, the approach to the purity of the titanium is not high, low efficiency.
Outlook has a superior performance of resource-rich and titanium from the second half of the 20th century as an ideal material of concern, but so far have not come from out of rare metals in the world's annual output of titanium is only tens of thousands of tons. As the Kroll magnesium reduction method is based on titanium tetrachloride to be sponge-like titanium, coupled with long processes, procedures and other factors more than the superposition, resulting in high cost of titanium sponge, the impact of a titanium applications in different sectors, so that many applications in the field has not yet been widely used. However, we believe that with the development of science and technology, the new titanium production process development, production costs, the expansion of production scale, the 21st century will truly become the century of titanium.
Into the workpiece surface to form a solid combination of metallurgical-type sediments. Discharge power cycle the host 10-3 ~ 10-1 s, high-frequency discharge and electrode rods (electrodes) in the high-speed rotating surface scanning, can be highly efficient large-area deposition coating.
Why can achieve "cold" (low heat input)?
That is because the discharge time (Pt) is shorter than the discharge interval time (It) during the discharge of heat quickly spread to other parts of the workpiece, so the heat will not work on the part of the deal and realize the true meaning of cold.
Why the bond strength is high?
Electrode rod (electrode) was an instant of arc ion and transferred to the workpiece in contact with the above, at the same time with the high temperature plasma arc (8000-10000 ℃) formed in the workpiece, such as under surface layer wrong with the section as a solid diffusion layer, the combination of high intensity will not fall off.
Features of precision die bonder cold patch:
- Advanced and reliable equipment, German native technology, world-class high-power argon protection, can work long hours.
- Rotary electrode damage, sedimentation, high efficiency welding, metallurgical combine dense coating quality.
- A multi-purpose machine can carry out welding deposition, surface hardening functions. By regulating the discharge voltage equipment, and discharge frequency, will be required to seek to strengthen the surfacing or coating thickness and smoothness.
- Simple operation, low heat input, preheat molds are not required to repair, the process of surfacing the moment no heat input, and therefore do not die deformation, non-annealing, biting edge and residual stress, mold or product does not change the state of metal.
- Source electrode Canton, economical and practical.
- ?Widely applicable to the substrate, including low-carbon steel, medium carbon steel, tool steel, stainless steel, tool steel, cast iron, cast steel, cast aluminum, aluminum alloy, copper alloy, nickel alloy, carbon-tungsten alloy, as well as all of the electrical conductivity of conductive body.
- Environmental protection, work process without any pollution.
- Economical efficiency, repair online at site is available, improve productivity, save time and costs.
- Repair of high-precision coating thickness from several microns to several millimeters, only grinding, polishing. Can also be vehicles, milling, planing, grinding and other machining, plating, etc., as well as post-processing.