The happiest thing when the news came out is, of course, these candidates, with double insurance, the tuition problem that had been in front of them before was solved by Principal Liang Qichao, and as soon as they came out, they were 1,000 full scholarships. When the candidates who were about to leave heard the news, they put down their packages and immediately plunged into intense revision.

Hu Wenkai's surrounding steps made everyone puzzled, and probably only Jiang Qiuming, Dai Jitao, Wu Hongxia, and Sun Xiaolan knew a rough idea in the Fujin Party. The surrounding areas are all subdued, and the cadres are almost trained, and Hu Wenkai only allows deterrence and does not allow occupation of the surrounding areas.

Zhou Haiquan and Hu Bin have no politics in their eyes, only research and development, and with the research and development base, the two of them simply regard the scientific research institute on Danfeng Street as their home. Three meals a day are soaked in scientific research institutes.

Coupled with Hu Wenkai's theoretical guidance, scientific research institutes have actually come into contact with powder metallurgy in a few months. This technology was only proposed in the sixties, and I didn't expect it to span forty years.

Powder production is the first step in powder metallurgy. Powder metallurgy materials and products continue to increase, their quality continues to improve, and the types of powder required to be provided are more and more. For example, from the perspective of the range of materials, not only metal powders are used, but also alloy powders, metal compound powders, etc.

From the point of view of powder shape, it is required to use various shapes of powder, such as when producing filters, it is required to form powder; From the point of view of powder particle size, powder of various particle sizes is required, and the particle size of coarse powder is 500~1000 microns, and the particle size of ultra-fine powder is less than 0.5 microns, etc.

In order to meet the various requirements for powders, there are also various methods for producing powders, which are nothing more than the transformation of metals, alloys or metal compounds into powders in a solid, liquid or gaseous state. Various methods for preparing powders and powders prepared by various methods.

This achievement has not yet been published has attracted many manufacturers in Tianfen base to visit, with the words of old Pete this thing can simply change the engine mileage, high temperature resistance leather durable, these two points alone are the lethal performance of the engine.

The most directly used in the aircraft manufacturing industry of Lao Pete, the brake pads, clutch friction plates, loose hole filters, porous sweating materials, oil-impregnated bearings, magnet cores, electrical contacts, high specific gravity alloys, cemented carbides and super-hard wear-resistant parts on aircraft engines can not be manufactured by ordinary casting and forging processes because they contain a large number of non-metallic components or contain connected pores, and can only be manufactured by powder metallurgy processes such as cold pressing and sintering.

The powder metallurgy materials used in the aerospace industry are more important than brake pad materials, loose hole materials and high-strength powder alloys.

Brake pads are the heart of an aircraft's wheel brakes. The landing speed of the aircraft is more than 200 km/h, the brake load is very large, and the instantaneous temperature on the surface of the brake pads can reach 800~1000 °C, and the bonding is not allowed, so as not to cause tire bursting caused by brake failure. Powder metallurgy brake pads made of iron powder or copper powder as the main ingredient and non-metallic powder that rubs and prevents bonding (can meet this requirement.)

The vast majority of military and civil aircraft use powder metallurgy brake pads. Because every brake will be worn, and the brake pads need to be replaced after 100~500 times, it is the largest powder metallurgy material made of the aircraft. Powder metallurgy materials

Porous permeable powder metallurgy material. Bronze or stainless steel filters used in turbine engine lubrication systems and aircraft hydraulic control systems are important components in preventing particulate clogging and seizure. The metal fiber loose hole material has good strength and plasticity, and can be used in high-temperature parts, rocket engine injector panels, sweat cooling loose hole materials for combustion chamber walls and throats.

These researchers thought about it and worked on a popular project: copper-iron-based powder metallurgy oil-impregnated bearings. This project is also a high-tech project in later generations, and I don't know if they are ignorant and fearless or daring.

Powder metallurgy oil-impregnated bearings use the porosity of the sintered body to impregnate 10%~40% lubricating oil and use it in the state of self-oil supply. During operation, the temperature of the bearing increases, and because the expansion coefficient of oil is larger than that of metal, it automatically enters the sliding surface to lubricate the bearing, and when the operation is stopped, the oil is sucked back into the pores as the temperature drops.

This thing is simply a home must-have for transmission equipment, but it is difficult to put into production after the theory comes out, and the difficulty of conceivable copper and iron-based powder metallurgy oil-impregnated bearings is made of copper powder and iron powder as raw materials, processed by mold pressing, high-temperature sintering, and vacuum immersion oil, powder metallurgy oil-impregnated bearings are generally mainly made of raw material powder by pressing, sintering, shaping, oil immersion and other processes.

Zhou Haiquan did not learn the essence of Hu Wenkai, but some small tricks were still learned very thoroughly, he organized the scientific research institutes and Far Eastern University to participate in the research, the steps and categories of division of labor to each group, each group issued 10,000 yuan of research and development expenses.

This trick is really smart, I rely on 10,000 yuan to convert the production cost and not the research and development cost, and each team does not blink their eyes and stretch out their hands to prepare the money. Hu Bin pressed his hand on a pile of money and said: "If you don't take it out and convert it to production, don't want to get one." ”

Money is the driving force, and soon, a practical technology is placed on Zhou Haiquan's desk.

The powder, blank or sintered body placed in the extrusion cylinder is pressed out through the specified die holes. According to different extrusion conditions, it is divided into cold extrusion and hot extrusion. Cold extrusion is to mix metal powder with a certain amount of organic binder and extrude it into a billet at a lower temperature (40 °C ~ 200 °C).

Powder hot extrusion refers to the metal powder pressing blank or powder packed into the sleeve heated to a higher temperature under extrusion, hot extrusion method can produce products and materials with complex shapes and excellent performance. The extrusion molding equipment is simple and has high productivity, and it is possible to obtain products with uniform density in the length direction.

Extrusion molding can extrude small micro-shaped tubes with very thin walls and straight warps, such as powder metallurgy products with a thickness of only 0.01mm and a diameter of 1mm; It can extrude dense powder materials with complex shapes and excellent physical and mechanical properties, sintered aluminum alloys and high-temperature alloys.

The transverse density of extruded products is uniform and the production continuity is high, so they are mostly used for strips and rods with simple cross-sections, and spiral bars and rods. From copper-iron base powder directly to sintered aluminum alloy, this leap is too big. This is not what surprised them, the following directly scared the two of them to death.

The powder is pressed in a stamper to make tools for lathes. The powder is pressed in a stamper. When pressing at room temperature, it generally requires a pressure of about 1 ton/cm2 or more, and when the pressing pressure is too large, it will affect the pressurization tool; In addition, layered cracks, scars, and defects sometimes occur in the body. The maximum pressing pressure is 12-15 t/cm2. When the ultimate strength is exceeded, the powder particles undergo crushing failure.

The developers explained that the powder in the floating negative die is pressed between a moving die punch and a fixed die punch.

The negative die is supported by a spring and is in a floating state, and when the pressure is started, because the friction between the powder and the negative die wall is less than the spring supporting force, only the upper die punches down and moves downward; With the increase of pressure, when the friction force of the two is greater than the spring supporting force, the negative die and the upper die punch go down together, and the relative movement is produced between the lower die punch, so that the one-way pressing is transformed into the two-way compression of the blank, and the pressure of the blank is not compressed at the same time in both directions, so that the density of the blank is more uniform.

Zhou Haiquan and Hu Bin held the powder die tool in their hands, and the hardness was twice as high as that of the tungsten alloy tool that the boss had obtained before. To be honest, some professional terms are too unfamiliar and harsh in the ears of the two of them, Zhou Haiquan is embarrassed to think about not going back to the pot and reinventing the words, and he really can't understand the words of these young people.

In all fairness, I have never heard the word repressurization, which is the application of pressure to improve the physical and mechanical properties of the sintered body, including finishing and shaping.

Finishing is the repression of the sintered body to achieve the desired size, and the sintered body is pressurized by the finishing die to improve the accuracy.

Shaping is a recompression to achieve a specific surface shape, and the pressure is applied to the product through the shaping die to correct the deformation and reduce the surface roughness value.

Even Hu Wenkai will be dizzy again after this professional terminology, let alone say that there are no knives, and other scientific researchers do not regard this thing as their main business at all, but as a by-product.

These guys introduced the term heat treatment, if Hu Wenkai wanted to laugh here, he began to prepare to use the term heat treatment in the end, I don't know what happened, if I knew that the Nanjing scientific research institute used the term he prepared, I don't know how to feel.

The explanation of heat treatment by these guys is that the sintered body is heated to a certain temperature, and then the cooling method is controlled to improve the performance of the product. Commonly used heat treatment methods include quenching, chemical heat treatment, thermomechanical treatment, etc., and the process methods are generally similar to those of dense materials.

For iron-based parts that are not subject to impact and require wear resistance, integral quenching can be used, and due to the existence of pores, internal stress can be reduced, and generally no tempering can be used. Iron-based parts that require external hardness and internal toughness can be quenched or carburized and quenched. Hot forging is a common method to obtain dense parts, and the hot forging products have fine grains, high strength and toughness.

Old Pete stayed next to him and grinned, almost all the materials on his plane were solved, and the aircraft skin produced by Hu Wenkai's formula was simply what Old Pete thought.

According to the number of parts, Hu Wenkai gave the following components of the aircraft skin: 50-70 parts of aluminum, 6-8 parts of zinc, 10-15 parts of magnesium, 0.05-0.07 parts of molybdenum, 0.03-0.05 parts of zirconium, 0.03-0.05 parts of titanium, 0.35-0.55 parts of manganese, 0.05-0.07 parts of vanadium, 5-10 parts of chromium, and 0.3-0.5 parts of boron.

Inexplicably, Hu Wenkai named this material 2A12 aluminum alloy, which is a kind of high-strength duralumin that cannot be strengthened by heat treatment. 2A12 aluminum alloy spot welding has good weldability, and there is a tendency to form intergranular cracks when gas welding and argon arc welding are used; , 2A12 aluminum alloy has good machinability after cold work hardening. The corrosion resistance is not high, and anodizing and painting methods are often used to improve the corrosion resistance by adding an aluminum layer on the surface.

Old Pete can see at a glance that this 2A12 aluminum alloy plate is used to make skeleton parts, skins, bulkheads, wing ribs, spars, rivets and other working parts below 150 °C on the aircraft.