Warm compacting process is a kind of new technology based on conventional molding process. Compared with conventional powder metallurgy (PM), warm compacting process require add special binder in the powder before compression and heating of moderate temperature lower than the conventional powder metallurgy desired temperature, then use conventional methods to obtain high-density powder compact was pressed. At present, warm compacting process can be widely used in some iron-based powder metallurgy parts fabricating, which can remarkably improve the density and properties of tungsten copper sintered body. We will discuss the process temperature and pressure applied on tungsten-copper material to analyze the impact of temperature and pressure from the temperature and pressure of pressing both temperature and pressure process of tungsten copper compacted density.

Temperature controlling plays an importance role in warm compacting process, in order to achieve the optimum temperature, related scholars at the same pressure do the compacting experiments at different temperatures. Experiment uses tungsten copper mixed powder (add 0.8% binder) at a pressure of 400MPa, at different temperatures for tungsten copper compacts pressed. Combined figure below we can see that the green density warm compaction under high pressure in cold forming the blank (at room temperature) as compared to the density. This is due to the cold pressing the powder in a binder lubricating can not work effectively, so the green density produced little effect; The temperature and pressure conditions in the binder may well play a role in improving the friction between the powder and the powder and die wall, thereby increasing the density of tungsten and copper compacts.

Metal sulfides can be generated by sulfur and metal, also can be generated from hydrogen sulfide (or hydrogen sulfate) reacting with metal oxide or hydroxide; it is a very important semiconductor material. With sulfide semiconductor playing an increasingly important role in  people's lives and production, metal sulfides nanometer materials are cause strong research interests of scientists because of their broad play application in photocatalytic material, luminescent materials, nonlinear optical materials and light-sensitive sensor material. Tungsten disulfide, as a sulfide with unique properties, causes particular concern because when the temperature exceeds the critical value, the magnetic and conductive properties would be changed. It is widely used in solar cells, catalytic hydrodesulfurization reaction, as well as a photoconductive material and lithium - sulfur battery cathode materials and other aspects.



Ammonium paratungstate can be used as raw materials to prepare tungsten disulfide nano-powder with aluminum sulfide shell.
1. Using the traditional process to reduce ammonium paratungstate to high purity tungsten powder;
2. Tungsten and aluminum blocks pressed under the pressure of IMpa~IGpa from powder as the anode material of the plasma arc furnace, wherein the tungsten atomic share the percentage of 95~99%;
3. Using graphite electrodes as the cathode, tungsten and aluminum blocks as the anode;
4. Preparing nanometer tungsten disulfide powder by Arc Discharge Plasma Technology
Holding the distance of cathode (graphite) and anode (tungsten and aluminum blocks) between 2~30mm, carrying out the reaction under the protection of argon and hydrogen sulfide gas, and the arc discharge voltage 10~40V, then tungsten disulfide nano-powder with aluminum sulfide shell generated.
Remarks: the partial pressure of argon and hydrogen sulfide gas is respected to 0.01~0.5Mpa and 0.01~0.3MPa.

Tungsten and molybdenum are similar elements, with very similar properties in physical and chemical. Generally, molybdenum will exist with tungsten in the ore, but different precision ore with different molybdenum content. For getting production process, completely and effectively separating tungsten and molybdenum is a necessary link in the production process ammonium paratungstate. In traditional tungsten smelting process, there are many problems in the removing molybdenum step, for example: impurities removed not completely, huge cost, complex process and resin difficult to desorption. Therefore, studies on deeply removing molybdenum with the process ensured simple, and control costs are becoming especially meaningful. According to the problems enumerated above, using a multi-amine weakly basic anion exchange resin in the production process of ammonium paratungstate by ion-exchange method for deeply removing molybdenum is proposed in this paper.



In this method, multiple amine weakly basic anion exchange resin is used as the stationary phase, and ammonium tungstate solution containing with thiomolybdate anion as the mobile phase, carrying out anion exchange adsorption to make the thiomolybdate anion selectively adopted by multi-amine weakly basic anion exchange resin, thus to achieve the goal of  separating tungsten and molybdenum effectively, and to obtain the high purity ammonium tungstate solution; then, further evaporation, concentration and crystallization to generate high purity APT crystals.
Noted: Multi-amine weakly basic anion resin can be desorption with low concentrations of sodium hydroxide solution (0.5mol / L), thus going to be reused.

The method that selectively removing molybdenum from tungstate solution by multi-amine weakly basic anion exchange resin has the advantages such as: effectively removal ; the resin can be reused to extend its service life; a short process, simple to operation, low cost, easy to applied in industrial.

There are many tungsten electrode types, so how to identify select and prepare tungsten electrodes is very important for your application.Tungsten electrode is an important part in TIG (or GTAW) welding. Because tungsten electrode has many good properties such as high hardness and high temperature resistance to carry the welding current to the arc, and it has the highest melting point of any metal so it can be used in high temperature environment and without quickly loss.

These non-consumable tungsten electrodes come in a variety of sizes and lengths and are composed of either pure tungsten or a hybrid of tungsten and other rare earth elements and oxides. According to the raw material it can be divided into these types: pure tungsten electrode, 2%thoriated tungsten electrode, 2% ceriated tungsten electrode, 1.5% lanthanated tungsten electrode, zirconiated electrode and other rare earth tungsten electrode. Choosing an electrode for the TIG process not only depends on the base material type and thickness, but also depends on welding alternating or direct current. There is a selection guide for selecting different type tungsten electrode.

Pure tungsten electrodes during welding can provide great arc stability for AC welding with balanced wave especially on aluminum and magnesium, but is not typically used for DC welding.
2% thoriated tungsten electrodes can increases electrode’s electron emission qualities, having lower consumption and eliminates arc wandering for greater stability. And it can use for welding some small thin steel and parts. But it has radioactivity and are only for specialty type AC welding.

2% ceriated tungsten not only can perform best in DC welding at low current settings but can be used proficiently in AC or DC processes. But using ceriated electrodes at higher amperages is not recommended.

1.5% lanthanated tungsten electrodes have excellent arc starting, low-burn-off rate, good arc stability and excellent re-ignition characteristics. It can work well on AC or DC electrode negative with a pointed end or they can be balled for use with AC sine wave power sources.

Zirconiated tungsten electrodes can produce an extremely stable arc and resists tungsten spitting. It is ideal for AC welding as it retains a balled tip and has a high resistance to contamination.

Rare earth tungsten electrodes has stable arc in both AC and DC processes, greater longevity than thoriated tungsten, the ability to use a smaller size diameter tungsten for the same job, use of a higher current for similar sized tungsten and less tungsten spitting.

2% thoriated tungsten electrode is the most commonly used electrodes among other tungsten electrodes. But with the environmental awareness increasing, thoriated tungsten electrodes now are gradually replaying by ceriated tungsten electrodes. Comparing these two different tungsten electrodes we will found they are a lot of similarities and differentia.

2% thoriated tungsten electrodes contain 97.30% tungsten and 1.70 to 2.20% thorium. It is the most commonly used electrode today. The reason why thoriated tungsten having widely application is it can increases electrode’s electron emission qualities, improving arc starts and allowing higher current carrying capacity. On the other hand, this electrode operation is far below than its melting temperature, so it has considerably lower consumption and eliminates arc wandering for greater stability. Besides, it has lower weld contamination level than other electrodes. What’s more, during manufacturing, thorium can evenly disperse throughout the electrode which allows the electrode to maintain a sharpened edge for welding thin steel. But, thoriated tungsten electrodes are only for specialty type AC welding, and they are exceptional for DC electrode negative or straight polarity on carbon and stainless steel, nickel and titanium applications. Further, thorium is radioactive. Therefore, during operation must always follow manufacture’s warnings, instructions and the MSDS for using.

2% ceriated tungsten electrodes contain a minimum of 97.30% tungsten and 1.80 to 2.20% cerium. It not only can perform best in DC welding at low current settings but can be used proficiently in AC or DC processes. But using ceriated electrode at higher amperages is not recommended. At higher amperages situation the oxides will migrate quickly to the heat at the tip, removing the oxide content and nullifying its process benefits. Ceriated tungsten electrodes have many excellent properties. For example, it can start the arc at low amperages and it is non radioactivity material, having longer service life than thoriaed tungsten electrode. On the other hand, ceriated tungsten electrode is widely used in orbital tube and pipe manufacturing, thin sheet metal work or small and delicate parts welding.