Every element counts in the high-precision, high-stakes gas atomization process. It starts with the molten metal, driven across an atomization nozzle by a blast of high-pressure gas. The end effect is a shower of droplets that, when cooling, crystallize into powder. The material qualities of the nozzle directly affect both the efficiency of this operation and the quality of the resultant powders. With their unique qualities, Boron Nitride Ceramic Nozzles have raised a new standard in this sector by offering answers that improve the final result as well as the process.
Gas Atomization Process
Production of alloy powders usually uses gas atomization. Using this approach, the following describes the processes for manufacturing alloy powders:
One mixing
The required alloy composition guides the combination of the metal raw components in a specific ratio.
2. Smelting
The ready materials are smelted furnace heated over the melting point of the metal to melt it into a liquid form.
3.atomization of gases
Under high-speed airflow, the molten metal liquid is crushed into microscopic droplets using a specifically-made nozzle.
4.Fourth: condensation
Quickly cooled and solidified in an inert gas or vacuum environment, the atomized droplets produce powders with good sphericity and uniform particle size.
5. Collecting
The condensed powder is gathered, filtered and graded to produce a powder product meeting specific criteria.
Process factors like temperature, flow, and gas pressure have to be controlled throughout the gas atomizing process to ensure the quality and performance of the powder. To get powders with more quality, numerous innovative tools and technologies including laminar gas atomization and limited nozzles can also be used.
Among various benefits are high sphericity, smooth surface, few satellite balls, low oxygen content, homogenous particle size distribution, good fluidity, and high apparent and tap density, etc. The gas atomized alloy powder Laser cladding, laser direct deposition (DLD), powder hot isostatic pressing (HIP), powder metallurgy (PM), metal injection molding (MIM), and other methods call for these powders.
Alloy powders like titanium, nickel, cobalt, and high-temperature alloys are produced using the gas atomizing technique extensively. Among the several sectors including electronics, biomedical, automotive, and aerospace, etc., these powders find major uses.
Material Selection for Gas Atomizing Nozzles
Under the gas atomization process, several materials could replace boron nitride ceramic nozzles as nozzles materials. The usual ones are listed here:
Materials ceramics
Although alumina ceramics are highly hard and resistant to high temperatures, their thermal stability and corrosion resistance may not be as strong as those of boron nitride.
Although some carbide ceramics, such as silicon carbide, have great hardness and high-temperature resistance, they could potentially be less than boron nitride in several other respects.
A few metal objects
Some special metals or alloys can also be utilized to create nozzles after suitable processing. Still, at high temperatures metal materials usually have a limited degree of corrosion and oxidation resistance.
Although these materials can be used as substitutes, boron nitride has several unique characteristics that clearly benefit the gas atomizing process. While some of different alternative materials show better performance in particular areas, they are difficult to reach the same degree of total performance as boron nitride.
Practically, the choice of alternative material calls for careful assessment of material performance, cost, process requirements, effects on powder quality, and other aspects. Furthermore, enough testing and investigations should be conducted in line with particular criteria to guarantee that the substitute materials can meet particular needs and guarantee the quality and performance of the powder.
Why Choose Boron Nitride Ceramic Nozzles
Though some special metals or alloys after appropriate treatment can be used to manufacture nozzles in the gas atomization process, their oxidation and corrosion resistance at high temperatures is generally poor, and their overall performance might not be comparable to boron nitride.
The patent "Technology of nozzles for preparing metal powders by vacuum gas atomization" details a nozzle used in vacuum gas atomizing metal powders. This nozzle's body features a spray hole on the lower end face and a metal liquid guiding chamber on the top end face. With many spiral grooves on the inner wall of the circular spray hole, it links to the guide hole. Under the effect of gravity and negative pressure, this design helps the metal liquid to be distributed and sprayed out in all directions, so increasing the crushing space of the first high-pressure gas spray and so lowering the particle size of the metal powder and improving the fine powder rate and applicability.
varied applications call for varied considerations of elements including material performance, cost, process constraints, and the impact on powder quality when selecting nozzle materials. In the manufacturing of gas atomized powder, boron nitride ceramic keeps providing enormous advantages with its unique properties—such as high hardness and wear resistance, low friction coefficient, thermal stability, improved corrosion resistance, and insulation. Although some other materials might excel in some particular fields, their general performance is difficult to equal that of boron nitride. Enough trials and testing carried out in line with certain gas atomizing criteria helps to ensure that the chosen materials can satisfy production circumstances.
Benefits of Boron Nitride Nozzles in Gas Atomization Powder Production
1.One's corrosion resistance
At high temperatures, boron nitride may resist the chemical erosion of molten metal, therefore allowing the nozzle to run consistently over a long manufacturing period. For atomizing some highly active metal alloys, for instance, boron nitride nozzles can effectively avoid damage from corrosion, therefore maintaining production continuity.
2. exceptional thermal stability
In high-temperature conditions, boron nitride ceramic resists deformation, therefore guaranteeing a stable atomization effect. This is absolutely necessary for consistently sized powders of good quality. Stable nozzle performance helps guarantee constant atomizing conditions every time creating high-temperature alloy powder.
3. Limited friction coefficient
This lowers the resistance of the molten metal as it travels through the nozzle, therefore allowing the metal liquid to flow out more naturally and improving the atomizing efficiency.
4. Get smoother powder.
Better particles produced by boron nitride nozzles lead to the creation of finer powder particles.
5.strong wear resistance and hardness
These features extend the service life of the nozzle and reduce its frequency and cost of replacement.
Six: low maintenance expenses
Especially in long-term, large-scale powder production, boron nitride nozzles can dramatically save the maintenance expenses.
7. insulation
Production Process of Boron Nitride Ceramic Nozzle
1. Sintering material preparation
Granulated silicon nitride, aluminum oxide, copper oxide, or zirconium oxide are equally mixed with boron nitride powder by dry technique using a pulverizer at a particular ratio.
2. Hot sintering by pushing
Inside a rubber bag lies the blended raw material powder. The bag is vacuumed and sealed; next, to condense the body, it is isostatically squeezed at 100–200 mpa for 60 minutes. The body is then inserted into the hot pressing mold and transferred to the hot pressing furnace after being adjusted to suit the inside chamber of the mold. Following vacuuming to 10 pa, heating begins and the vacuum state is maintained until 1000–1200°C. Under the flowing nitrogen environment, the temperature keeps rising as nitrogen is filled to an atmospheric pressure.
The pressure rises gradually when the temperature gets to 1500°C. The pressure rises to 25–30 mpa when up to the maximal temperature of 1800–1850℃; the temperature and pressure are kept for 0.5–3 hours. Then cease heating and let it cool naturally; maintain the steady pressure during this process. The pressure loses with decreasing temperature when the temperature drops below 1200℃ since it loses its maintenance. The temperature falling to 800℃ releases the pressure. The furnace can be opened to remove the mold when its temperature drops to 80°C; the temperature keeps lowering until it reaches room temperature. After that, the sintered body is removed from the mold.
3. Methodical processing
A CNC lathe and a manufacturing center shape the hot-pressed sintered body into a ceramic nozzle. The body is sliced using a CNC diamond wire cutting machine.
In some specialized gas atomizing processes, such those using electromagnetic induction heating or electric field control, the insulating qualities of boron nitride help avoid current interference and improve process stability.