In the early 1980s, some researchers have proposed the distribution of the drill bit buttons should follow three guidelines: 1. each cutting button has equal rock breaking volume; 2. equal wear rate; 3. equal rock consumption. Meet these three criteria in order to ensure rock breaking energy evenly distributed on each cutting tooth, so as to obtain the best rock-breaking effect. Theoretically, the process of tungsten carbide buttons for rock breaking can be divided in to three steps: elastic deformation (when the force is released, the rock surface can restore the status), fatigue process (also known as pressure crushed stage, surface cracks do not disappear and fracture rock surface) and volume breaking (The formation of shear body, under increasing pressure formed pit crushing).

When the adjacent tungsten carbide buttons impact the rock at the same time, the overall crushing effect depends on the nature of the deformation of the cross-belt. Reasonable button spacing will produce elastic deformation energy to rupture and push the rocks out with the increasing load; if the spacing of two buttons is too narrow, it will make the compacting zone too close to increase the difficulty of the shear rock; if the spacing of two buttons is too wide, the rock in the middle part will not be cracked and form rock ridges. Viewed from the impact energy, for the drills fixed diameter, the less number of buttons, the more impact energy of each button endure and the rock crushing volume will also increase accordingly. However, if the number of button is too small, which over the stress fracture of a single button, tungsten carbide button will be broken.

Buttons distribution firstly depends on the shape of the bit end face, which includes flat-shaped, arc-shaped, protruding, concave shape, and so on. The most used are flat-shaped and arc-shaped. Generally, tungsten carbide drill bit with large diameter usually uses arc end face and the small diameter often uses the flat-shaped. In intermediate buttons distributed in the cross section perpendicular to the bit axis, while the button are located on the inclined face of the drill bit. The outermost edge of buttons not only has to be mechanical support, but also should withstand the crushing function so that it has a greater amount of consumption than the buttons middle. Furthermore, it has high speed of linear velocity and requires a larger diameter, wider distribution and excellent quality.

The main component of tungsten carbide button is the hard phase of WC and the binder phase of Co, which has high hardness, high strength, excellent wear resistance and corrosive resistance and perfect impact resistance. So it can be widely used in high-pressure DTH (drill-the-hole), oil drilling, tunneling, mining industry and civil architecture. Due to its excellent wear resistance and impact resistance, compared with other materials, and it has higher drilling speed and the life span of drills and bits will be extended so that it does not need to change buttons constantly, which improves the overall efficiency and reliefs the labor.

On the basis of ensuring the stable properties of tungsten carbide buttons, the quantity and the distribution of buttons on drills and bits are also the significant factor on drilling performance. The essence of .tungsten carbide button distribution optimization on drills is based on keeping the excellent drilling properties and has the least number of buttons and the best location. Practically, a reasonable distribution of tungsten carbide button is beneficial for reducing the consumption of rock drilling, improving the drilling rate and in case of the wear of cutting buttons early to ensure the best cutting performance. Take DTH drill as an example, the bottom center of the distribution by the number of buttons surrounded, and one of the lowest penetration rates determines the drill bit ROP (rate of penetration), and the lowest life expectancy button also determines the life of the drill bit.

With the development and application of modern science and technology, radiation technology has gradually entered people's daily life and played a vital role in the power generation, industrial, medical and other aspects. Radiation sterilization is a successful example of radiation technology, which is mainly used for the disinfection of disposable medical supplies and medical instruments by using ionizing radiation to kill pathogenic microorganisms (including viruses) to eliminate their poison. The secret of radiation sterilization is the radioactive isotope Co-60. Co-60 is a radioactive isotope of cobalt element that can decay into Ni-60 through β decay while emitting high-energy, high speed electron and two beams of gamma rays. Radiation sterilization is the use of these gamma rays to irradiate bacteria and viruses hiding in the medical supplies and medical equipment, resulting in physiological dysfunction, making it cannot able to grow and develop, or even causing death. The medical instruments to be disinfect by using radiation are mainly blood, surgical instruments, artificial heart and lung, suture materials, injection equipment, transfusion equipment, catheters, bandages, dressings, birth control appliances.

Gamma ray, also called gamma radiation, is extremely high-frequency electromagnetic radiation and therefore consists of high-energy photons. When the body is irradiated with gamma-rays, gamma rays can enter the human body and erode the organic molecules (such as proteins, nucleic acids and enzymes organic molecules which constitute living cells), disturbing the chemical process inside human body, and even leading to cell death. Thus, medical workers should take certain precautions during the process of radiation sterilization of medical devices. In addition to time protection (reduction of exposure time), distance protection (away from the radiation source as far as possible), putting a shielding between man and sources to weaken the intensity of the radiation is also a good protective measures. The radiation shielding generally used for shielding radiation is tungsten alloy radiation shielding.

Due to the radiation sterilization is widely used in disinfection of medical devices in recent years, thus tungsten alloy radiation shielding for sterilization of medical devices can be used to shield radiation produced during the process of radiation sterilization. According to relevant research, the shielding performance of a metal material increases with the increasing of its density, therefore tungsten alloy radiation shielding for sterilization of medical devices has great shielding effectiveness with the high density of tungsten alloy, so that can efficiently absorb and shield radiation produced by the process of sterilization of medical devices, to weaken the intensity of the radiation, and prevent medical personnel from being subjected to radiation damage.

The liner is the key component of perforation bombs and armor-piercing, whose performance directly affects the penetration depth and piercing armor-piercing shells and after the explosion. In the early days, it uses turning process to fabricate copper rods and iron rods to form the liner shape or press-molding process to copper plate and iron plate. But these process has lower productivity, low dimensional accuracy and less prone to clogging of the perforation. With the development of powder metallurgy, powder sintering gradually replaced the cover plate liner, the production process is simplified, and overall efficiency has been improved.

However, due to the cover wall is thinner, easily deformed during sintering, poor surface fineness, it needs some optimization. Warm flow compaction can form the large component with a complex shape or structure and uniform density distribution, which is beneficial for the further expansion of tungsten copper material applications. It combines the advantages of injection molding and warm compacting process, which improves the flowability of the mixed powder by the viscosity changing of the binder. There are some experiments shows that the density distribution of W-70Cu liner by warm flow compaction is more uniform and the penetration is more stable.

Overall, compared with the injection molding suitable for the smaller components, warm flow compaction is more suitable for the larger components with complex structure and shape. It has higher requirements on the granularity of raw material and is sensitive to the temperature changes and the amounts of binder. Low temperature may cause mixing powder flow properties deteriorated, so that the tungsten copper shaped charge density distribution can not be molded or uneven. High temperature may obviously separate the two phase (the mixed powder and the binder). The excessive amount of adhesive may cause infiltrated tungsten skeleton pore through the large, so that the density decreases and easily deformed. In addition, warm flow compaction combines the advantages of injection molding and warm compacting process, and it can effectively improve the density, the penetration depth and armor capability of tungsten copper liner, which is the ideal choice for tungsten copper liner manufacturing in the future.

Grinding
Grinding electrode will produce radioactive dust into atmosphere. So it is recommended during grinding should make up a dedicated grindstone and local dust extraction. Besides, a simple filter mask is necessary unless you contact with small number of electrodes (less than about 20 per year). On the other hand, if the grinding wheel is not fitted with a protective viewing screen, eye protection should be worn. What’s more, the air extract from the grindstone should be collection so that the particles are deposited into a substantial disposable bag and will not release to the atmosphere just in case of ingestion or inhalation by welders.

After finish welding process, the area round the grinding wheels should be cleaned daily with a vacuum cleaner to remove dust particles. Besides, welders should be encouraged to wash their hands or whole body.

Welding
Some hazardous substance of thoriated tungsten electrode does occur during welding but it is a very small amount and the corresponding level of radioactivity is extremely low. However, wearing mouth, nose and eye protection during welding would further reduce any risk of contamination, and make welders more safety.

Alternatives to thoriated tungsten electrode
Lanthanum, cerium, yttrium and zirconium oxides can all be used with tungsten to produce lanthanated, ceriated, zirconiated and yttriated tungsten electrodes. Compared with thoriated tungsten electrode, they are all marginally radioactive, so the risk is even lower than with thorium oxide, so no specific precautions are needed. At the present, especially in developed counties they prefer to use these electrodes to place thoriated tungsten electrode. Among these rare earth tungsten electrodes, ceriated or lanthanated tungstens electrode are acceptable alternatives to thoriated tungsten electrode, particularly with a DC current, while zirconiated tungsten is preferred for AC current welding. There are very minor differences in the arc voltages required for equal currents between the various alternatives. Consideration should be given to justifying the use of thoriated tungsten electrodes in preference to other suitable alternatives.