Continued from the preceding paragraph, Either iron-based materials or tungsten (W), copper (Cu), aluminum (Al) and other metal powder, warm compacting process can be adapted, which also has many advantages, such as:

3. High compacting strength: at the same level of density, temperature and pressure through the green strength of conventional pressing process up compacts 1.25 to 2.0 times, which also facilitates the manufacture of complex mechanical parts powder metallurgy techniques to improve the powder metallurgy technology market competitiveness. Further, since the temperature and pressure after forming green strength is high enough so that it can compact simple machined directly in front of the sintering process, which improves the overall efficiency and the service life of tools;

4. Small release pressure: Compared to the conventional pressing process, stripping process in warm compaction pressure fell by more than 30%. This means that to a certain extent can reduce mold wear to extend its service life and easy-to suppress parts of complex shape. Moreover also by reducing the amount of feed powder lubricant, making the overall density of the compacts have been further improved;

5. Small elastic aftereffect: dimensional change after the sintering temperature and pressure process than conventional tungsten copper parts pressing process is much smaller sintering shrinkage is also smaller and easier to improve the dimensional accuracy of tungsten copper parts;

6. Excellent mechanical properties: in the case of material with the same density, temperature and pressure process using material prepared than the ultimate tensile strength of the multi-pressure sintering improved about 10%, the fatigue strength increased 10-40%;

7. Low relative cost: Although the temperature and pressure of the relative cost compared to the conventional process once the pressing process has increased the cost, but it is still lower than sintering process, copper leaching process, powder forging process.

In addition, in order to make tungsten copper products have excellent comprehensive properties, tungsten copper composite powder warm compacting process should focus on some main parameters, which includes the powder (granularity, content, porosity, apparent density, etc.), the lubricant additives (effect on temperature, friction factors, volatility, oxidizability, etc.), temperature controlling.

Warm compacting process is a kind of new process of high precision powder metallurgy that develops based on conventional molding process. Compared with conventional process, warm compacting process is in the process of pressing the powder in a conventional method and the mold is heated to a certain temperature after pressing to obtain a high-density powder compacts, which flies high density and high performance sintered body. Generally, the pre-heating temperature is between 100-150℃. Due to it is at the range of the room temperature and hot pressing temperature, which is so-called warm compacting. The standard warm compacting process can be density iron-based parts increased from room temperature to suppress (600 ~ 800MPa) of 6.6-6.8g / cm to 7.25-7.45g / cm, and the process cost and lower than the pressure recovery, re-burn, copper infiltration, forging.

In addition, this method can be obtained by pressing a high-performance powder metallurgy products, its high efficiency, high precision characteristics has become one of the faster process of powder metallurgy parts production technology in development. Either iron-based materials or tungsten (W), copper (Cu), aluminum (Al) and other metal powder, warm compacting process can be adapted, which also has many advantages, such as:

1. High density of compacting and sintering: Under the same compacting force, compared to conventional pressing process density can be increased 0.15-0.30g / cm3. Corresponding density required to obtain communication pressing force can be reduced by about 140MPa. This allows suppression of a larger size in the powder press lower tonnage, moderate density of powder metallurgy (PM) parts to create the conditions to increase the tonnage of the press;

2. Uniform compact density distribution: using warm compaction density tungsten copper fittings difference between conventional pressing process is lower than 0.1-0.2g / cm3;

Electrochromic material that is the material occurs by adding material to an electric field. Electrochromic mechanism is more complex, tungsten trioxide (WO₃) is an electrochromic material first to be discovered, and it is also the first to be made of electrochromic devices, but its color principle has been a controversial topic. Researchers studied by performing color performance, established a variety of models to explain the mechanism of color, for example, color center model, price between charge transport model, polarization model, free carrier models, but these models can not explain tungsten trioxide electrochromic mechanism.

Although there are not mechanisms for tungsten trioxide electrochromic, researchers had already learned how to apply tungsten trioxide electrochromic properties and has made tungsten trioxide electrochromic devices come out, and tungsten trioxide electrochromic properties has applied in many areas of life.

There have been a variety of different structures of tungsten trioxide electrochromic devices. As the illustration shows the sandwich-type five-layer structure of the electrochromic device of tungsten trioxide is transparent glass. The upper and lower layers are the cover layer; and the five middle orders from the top are the transparent conductive layer - the electrochromic layer - ionic conductor layer - ion storage layer - transparent conductive layer.

When current flows through a conductor, the conductor may have a fever, this heat generated by the current, called electric, or it can be understood as electric power is generated by the heat, the phenomenon of electrical energy becomes into internal energy. The use of electric principle can be made into various electric heaters, such as electric irons, electric stove, electric irons, electric ovens, water heaters, electric hatch boxes.

Electric material is a new energy material which has relatively traditional energy with small size, no noise, no pollution, long life and other characteristics. Thermoelectric materials can be used as electricity and thermal energy conversion intermediary material. The material will appear the temperature difference, and this electric conversion is reversible. Conventional thermoelectric materials have high ZT value (figure of merit, the higher the coefficient, the higher thermoelectric conversion efficiency), and the preparation of a mature technology, it has been widely used in thermoelectric power generation and refrigeration device. Some researchers are finding new thermoelectric materials, although these materials have a higher ZT value, it is the most toxic and precious metal alloys division, the use of these materials will increase in the environment.

Tungsten trioxide (WO₃) as important high-tech materials in the electrochromic, the light catalytic degradation, the gas detection and other areas has a wide range of potential applications. WO₃ is an n-type thermoelectric material at the same time. Currently, the status quo is thermoelectric materials research with P-type thermoelectric material, but it is necessary for the production of thermoelectric devices p-type matches with n-type. Early, studies have shown that WO₃ doped thermoelectric performance, which has been improved. If we find a important dopant and it will be the best process parameters for WO₃ thermoelectric properties, it is possible to WO₃ used in thermoelectric materials.

Anatase nanometer TiO₂ is mainly used as activity carrier for denitration catalyst. Because of TiO₂ composites with WO₃ in TiO₂-WO₃-SiO₂ powder, the structure and surface properties have been changed. Also it causes WO₃ distributing more uniform, thus improve the processing performance which is advantageous to mixing, extruding, drying process, thus ensure  rate of finished products. We propose a method for preparing composite powder TiO₂-WO₃-SiO₂, and the specific steps as follows:

1. Beating and dispersing the raw material H₂TiO₃, and then adjust the concentration of titanium dioxide slurry;
2. Add ammonium paratungstate and white carbon black into the slurry;
3. Add ammonia to adjust pH to 5.5~8.5 for improving combination with WO3 and the calcination properties of metatitanic acid;
4. Filtrating and dehydrating the slurry to get massive cake, in which mass fraction of TiO₂is controlled in 40%~55%;
5. Crushing massive cake mechanical, then drying it at 200~380℃ for 2.5 hours, and then calcined 380~680℃ for 4.5 hours;
6. Crushing to generate the required composite powder TiO₂-WO₃-SiO₂.

The method descripts above has the following advantages:
1) Low manufacturing cost, simple process;
2) The products obtained are not only with long service life and high surface area, surface chemical activity, good processing performance, but also have the advantages of high mechanical strength and resistance to erosion.

The activity of SCR denitration catalyst in-service will decrease by being abraded from flue gas, deposited from solid material, poisoned from alkali metal. And then after 2 or 3 years the catalyst would lose activity and end its life. Cleaning the SCR denitration catalyst is becoming very necessary because it costs high, and belongs to consumables. At the same time, the waste catalyst is difficult to handle because of the toxicity which will cause secondary pollution to the environment easily. We push a method for cleaning SCR denitration catalyst on the production process, steps as following:



1. Configure the cleaning solution
Stirring with a machine to mix oxalic acid solution, dispersing agent MF, ammonium metavanadate and ammonium paratungstate for more than 10 minutes for generating cleaning solution. Among them, the mass concentration that MF is 0.1-1wt%, ammonium metavanadate is l-3wt%, and ammonium paratungstate controlled at 5-15wt%. The pH value of the oxalic acid solution supposed to be 5-7;
2. Blowing and cleaning the surface of SCR denitration catalyst by a sonic soot-blower for 15s, and then cleaning the surface and pore of catalyst for 1min in certain circumstances;
3. Washing the SCR denitration catalyst for 5mins, and collect the waste liquid at the same time;
4. Washing the SCR denitration catalyst with cleaning solution for 10-20mins, also the waste liquid should be collected;
5. Dry the catalyst through a hot air drying device for 2-4 hours, thus finish the progress of cleaning SCR denitration catalysts.

Tungsten carbide ball double V-slot grinding can ensure that the rotation angle of the ball will change with sphericity, but it requires that the grinding tray V-slot up and down has higher properalignment and shape error and assembly error institutions needed to be effectively controlled, otherwise the blank ball can not roll along the groove smoothly. The relevant domestic scholars have done a lot of this research and developed a conical grinding method in which the abrasive disk is tapered, which makes carbide ball blank has a large corner across from the milling process (usually up to 45 ° left and right), to obtain a full rotation, enhanced rotary slide ball blank, improving overall processing efficiency. The following is a schematic view of the three grinding work mode, you can clearly see different from the design of the grinding tray:

Besides these three kinds of conventional grinding methods, Related researchers and academics abroad in order to achieve high-speed grinding ceramic balls have also proposed a flexible and high material removal rate of magnetic fluid polishing. Its basic principle is to use magnetic fluid mixing abrasive particles as an abrasive, when the magnetic fluid is given a certain magnetic field, the magnetic fluid will produce upward thrust, by the corresponding floating disc ceramic balls implement processing load. It remarkably improve the efficiency of precision ceramic ball and its roundness error less than 0.14μm, surface roughness reaches 0.01μm, material removal rate reaches 12μm / min, which is more than 40 times that of conventional grinding method.

However, this method due to the complex structure, inconvenient operation, and the magnetic fluid itself heightening price, after the magnetic fluid and particles worn when machining, material removal will be affected to some extent, it is also the emergence of a non-magnetic fluid polishing (water and glycerol mixture) instead of magnetic fluid and resin bonded diamond grinding wheel instead of embedding the abrasive grinding tray. Although the processing efficiency and processing efficiency and non-abrasive magnetic fluid magnetic fluid grinding pretty, its precision can not be fully guaranteed, both of structure of them are relatively complex, which is not suitable for large-volume production of high-precision machining of tungsten carbide ball.