The Application of Industrial Gases in the Mechanical Manufacturing Industry
In addition to their widespread use in metallurgical and chemical industries, industrial gases also have a very broad application in the mechanized manufacturing industry in terms of reaction industrialization.
The mechanical manufacturing industry refers to the industry that produces various types of machinery and equipment, such as power machinery, lifting and transportation machinery, agricultural machinery, metallurgical and mining machinery, chemical machinery, textile machinery, machine tools, tools, instruments, and other mechanical equipment. The mechanical manufacturing industry provides technical equipment for the entire national economy, and its level of development is one of the main indicators of industrialization and an important pillar industry.
Metal Cutting and Welding
The application of oxygen in the mechanical industry for metal welding and cutting can greatly improve work efficiency. Hydrogen-oxygen flame and oxygen-acetylene flame are commonly used for cutting and welding metal sheets and containers in mechanical factories. The oxygen-propane flame cutting can improve the smoothness of the cutting surface and replace some parts that were previously cast, forged, milled, or created. Oxygen itself is used as a combustion aid in combination with flammable gases such as acetylene and propane to achieve the effect of welding and cutting metals. Its wide range of applications, particularly in mechanical enterprises, makes it a very convenient method for cutting.
1, Metal Heat Treatment
Ammonia is a neutral gas. In its unactivated state, nitrogen can be used as a protective heating gas to prevent oxidation and decarburization of steel, and is widely used in heat treatment processes such as bright quenching, bright annealing, and bright tempering. In vacuum heat treatment, nitrogen gas is often used as a cooling medium. When pressurized oil quenching is used with nitrogen, it can protect the electric heating elements of the vacuum furnace and improve the hardenability of the steel by adjusting the nitrogen pressure. Under certain voltage and low vacuum conditions, nitrogen can be ionized for ion nitriding and ion nitrocarburizing. During carburizing and nitriding, nitrogen is commonly used for blowing, exhaust gas, and sealing the furnace door with a gas curtain to prevent oxidation cooling after carburizing. When the gas is turned off and power is cut off, nitrogen can be introduced into the furnace to prevent furnace gas and ensure safe operation. Nitrogen-based atmosphere treatment has the advantages of energy saving, abundant gas sources, safety, economy, and wide adaptability. It can be stably used for various heat treatment processes such as annealing, quenching, carburizing, and nitriding. To produce high-quality euro coins, the steel alloy coin punch used in the manufacturing process must undergo special heat treatment.
2, Low-temperature treatment of metals
Liquid nitrogen can rapidly transform residual austenite structure into a hard, dense, and stable martensitic structure, which can increase the durability of metal parts by 0.5 to 1.5 degrees. It is widely used in rolling mills, train wheels, cutting tools and other fields. In addition, low-temperature treatment can also improve the lifespan of parts such as molds, camshafts, gears, and can be applied to materials such as stainless steel, hard alloys, non-ferrous metals, and even plastic glass.
High-purity nitrogen gas, along with high-purity ammonia gas and high-purity carbon dioxide, is used as the active medium in laser cutting machines.
4, Welding processing
It is used as a shielding gas for processing aluminum products, aluminum profiles, and aluminum foil rolling, as well as an expanding gas for shielding in reflow and wave soldering to improve the quality of soldering.
5, Chemical cleaning of a drilling furnace
The use of nitrogen gas top blowing during the disposal of waste liquid through hydrofluoric acid cleaning and ammonia washing in the drilling furnace can achieve better rinsing results and prevent secondary corrosion of the inner cavity of the drilling furnace.
6, Tire industry
1) Improve the tire driving stability and comfort
Nitrogen gas is an almost inert diatomic gas with extremely inactive chemical properties. Nitrogen molecules are larger than oxygen molecules and are less susceptible to thermal expansion and contraction, resulting in a smaller degree of deformation. Its permeation speed through tire walls is about 30~40% slower than that of air, which can maintain stable tire pressure, improve tire stability during driving, and ensure driving comfort. Nitrogen gas has low audio conductivity, equivalent to 1/5 of ordinary air, and using it can effectively reduce tire noise and improve driving quietness.
2), Prevent flat tire and lack of air running
Tire blowouts are the number one killer in road traffic accidents. According to statistics, 46% of traffic accidents on highways are caused by tire failures, of which tire blowouts account for 70% of the total tire accidents. When a car is driving, the temperature of the tire will increase due to friction with the ground. Especially during high-speed driving and emergency braking, the temperature of the gas inside the tire will increase rapidly, causing a sudden increase in tire pressure and the possibility of a blowout. High temperature can also cause rubber aging, fatigue strength reduction, severe tire wear, and is another important factor that may cause blowouts. Compared with ordinary high-pressure air, high-purity nitrogen gas has the characteristics of being oxygen-free, almost free of water and oil, low thermal expansion coefficient, low thermal conductivity, slow temperature rise, and non-flammable, which greatly reduces the probability of tire blowouts.
3), Extend tended tire service life
Using nitrogen can greatly reduce the possibility of irregular friction on tires, such as crown grinding, shoulder wear, and bias wear, by stabilizing tire pressure and minimizing volume changes. This can improve tire lifespan. Rubber ages due to oxidation by oxygen molecules in the air, resulting in a decrease in strength and elasticity and the development of cracks, which can shorten tire lifespan. Nitrogen separation equipment can effectively remove oxygen, sulfur, oil, water, and other impurities from the air, reducing the degree of oxidation in the tire liner and preventing corrosion of the rubber. This can extend tire lifespan and greatly reduce the risk of vehicle rusting.
4), Reduce fuel consumption and protect environmental protection
Insufficient tire pressure and increased rolling resistance due to heating can cause increased fuel consumption when driving a car. Nitrogen, on the other hand, can maintain stable tire pressure, delay the decrease in tire pressure, and reduce rolling resistance due to its dryness, lack of oil and water, low thermal conductivity, and slow temperature rise. This reduces rolling friction and achieves the goal of reducing fuel consumption. Aircraft tires are filled with nitrogen because nitrogen is an inert gas with low permeability in tires, which can maintain stable tire pressure, reduce the probability of tire bursts, extend tire lifespan, reduce tire vibration on uneven road surfaces, and make vehicle travel more stable. Nitrogen also has the function of low sound transmission, greatly reducing the noise generated when the tire comes into contact with the ground. Especially in high-heat weather conditions, nitrogen-filled tires can fully demonstrate their advantages when driving on highways at high speeds.
Using the inertness of argon, chlorine can be used as a protective gas during electric welding to prevent oxidation, nitriding, quenching, and corrosion of materials such as titanium, platinum, alloys, and stainless steel.
1, Gaseous carbon dioxide
Carbon dioxide gas shielded welding can be widely used for welding various materials. Its protective effect is not as good as other rare gases (such as argon), but it is much cheaper in price.
2), Machine casting
Carbon dioxide can be used as an additive in the machine casting industry, which is conducive to machine manufacturing.
2, Solid carbon dioxide (dry ice)
1), Mold and other cleaning
Dry ice can be used to remove resin, degraded release agents, carbon deposits, oil stains, and to clear blocked exhaust holes in tire molds, rubber molds, polyurethane molds, polyethylene molds, PET molds, foam molds, injection molds, alloy die-casting molds, and hot and cold core boxes used in casting. After cleaning, the molds will be as shiny as new.
2), Car cleaning
Cleaning car door seals, canvas tops, interiors, and undercarriages can remove oil stains without leaving any water residue, avoiding water pollution. Traditional methods for cleaning carburetors or removing paint from car surfaces often involve lengthy chemical treatments that are harmful to human health. Carbon buildup can also be a problem in engines. However, using dry ice blasting can quickly and thoroughly remove carbon buildup within 10 minutes, achieving a 100% removal rate while saving time and reducing costs.
1, Production of electric vacuum materials and devices
In the production of electric vacuum materials and devices such as tungsten and platinum, hydrogen gas is used to reduce oxide powders, which are then processed into wire and strip. The finer the tungsten or platinum powder obtained, the higher the purity of hydrogen used, the lower the water content, and the lower the reduction temperature. The purity requirement of the filling gas, such as hydrogen thyratrons, ion tubes, and laser tubes, used in some gas-filled electron tubes is even higher, and the purity of hydrogen used in the manufacture of image tubes is greater than 99.99%.
2, Make amorphous silicon solar cells
In the manufacture of amorphous silicon solar cells, highly pure hydrogen gas is also used.
3, Application and development of photoconductive fibers
The application and development of optical fibers is one of the important signs of the new technological revolution. Quartz glass fiber is the main type of optical fiber, and during its manufacturing process, hydrogen-oxygen flame heating is required, followed by multiple depositions, which demand high purity and cleanliness of hydrogen gas.
Hydrogen gas and oxygen gas can be used for welding. The temperature of the combustion of hydrogen in oxygen can reach 3100K. When hydrogen passes through the flame of the arc, it decomposes into atomic hydrogen, and the generated atomic hydrogen flies towards the welding surface. The metal is further heated and melted by absorbing the heat of atomic hydrogen, so that the temperature of the welding surface of the metal reaches 3800-4300K. This atomic hydrogen can be used for melting and welding of refractory metals, high carbon steel, corrosion-resistant materials, non-ferrous metals, and so on. The advantage of welding with atomic hydrogen is that the hydrogen atom beam can prevent the welding area from being oxidized, so that no oxide scale is produced at the welding site.
5, Low temperature
As hydrogen is a gas with an extremely low boiling point, second only to ammonia, liquid hydrogen evaporates in a vacuum, which can achieve a low temperature of 14-15K. Therefore, hydrogen is commonly used as a refrigerant in scientific research that requires ultra-low temperatures.
Due to the non-reactive chemical properties of ammonia, it is commonly used as a shielding gas for welding of metals such as magnesium, diamond, aluminum, and Qin. When these metals are heated or melted, an inert gas atmosphere must be used to prevent them from reacting with oxygen and nitrogen in the air. A large amount of ammonia is consumed in metal welding processes. In inert gas shielded tungsten arc welding (TIG), continuous ammonia or ammonia-chlorine mixture is used to protect the non-melted tungsten electrode, the hot metal filler, and the welding area. The gas mixture used for shielding welding can be formulated with hydrogen and chlorine in different proportions. Depending on the welding process, welding wire, and base material, the composition of the gas mixture can vary. Typically, the ammonia content in the ammonia-chlorine mixture is 15%-70%, and sometimes about 0.015% of ammonia is added.
Ammonia and its mixtures with other gases are used as working media in plasma arc devices to produce plasma jets of over 50,000K, which are used to cut metals and spray heat-resistant alloys and ceramics.
3, Subzero treatment
Due to the chemical inertness of ammonia, it exhibits ideal gas behavior at all temperatures except for extremely low temperatures. It also has high specific heat capacity per unit mass, low viscosity, and high thermal conductivity. As a result, gaseous ammonia is commonly used as a working medium in closed-cycle low-temperature refrigeration systems. Liquid ammonia can generate extremely low temperatures needed for solid-state physics research.