The role of vacuum in synthetic diamonds' production
Mention diamonds and most people will associate that with the jewelry sector. They will also have in mind that such gems are to be found in mines and sometimes won under severe conditions (“blood diamonds”). For such reasons, the industry already investigated in the 1950s how to produce synthetic diamonds.
Today, there are several processes available to create artificial diamonds. Not only for jewelry where even experts are challenged to differentiate a natural diamond from an artificial, but also for the much larger market for diamonds in the industrial sector.
Four outstanding properties of synthetic diamonds
The key properties of synthetic diamonds that make them so interesting for the industrial sector are:
- Mechanical (superior hardness a chemical inertness)
- Optical (high transparency)
- Electrical (semiconductor properties)
- Thermal (highest heat conductivity)
Some typical industrial application examples are machining and cutting tools, window material for transmitting infrared and microwave radiation, and heat sinks for lasers and transistors. Synthetic diamonds are also the base material for semiconductor wafers and Qubits for quantum computing.
How are diamonds obtained?
Traditionally diamonds were naturally formed billions of years ago in the earth’s crust by carbon atoms being exposed to intense heat and pressure. However, due to technical advances, a new source of synthetically grown diamonds was created. This market can be divided into 2 main manufacturing methods:
- HPHT (High-Pressure High Temperature)– This method is based on how diamonds were naturally formed - compress carbon and add heat. The equipment footprint often has large and limited process control.
- CVD (Chemical Vapor Deposition)– This method is based on creating a vacuum environment and then introducing specific gasses to trigger a reaction. The equipment footprint often has a small and excellent process control.
MPCVD (Microwave Plasma CVD) growing process
Due to its small footprint and excellent process controls, the MPCVD growing process has gained in popularity. One important part of the MPCVD process is the creation of and maintaining optimal vacuum conditions inside a growth chamber. A typical growth chamber setup looks as below:
Synthetic diamond-making process. Source: NNE, 2019
The typical process steps are the following:
- Layout diamond seed/substrate
- Close chamber and evacuate chamber for conditioning, heat up substrate
- Introduce hydrogen
- Turn on microwaves and generate plasma (~4000 °C) above the substrate
Introduce process gases and start epitaxial growth
- Methane – carbon source
- Ethanol, Acetone, or Oxygen (optional) – helps improve the quality through oxygen plasma etching effect
- Nitrogen (optional) – helps speed up the process (learned from experience and made MPCVD growing feasible economically)
- 1 to 4 weeks of growth period
Which are the vacuum pump requirements for the growth period?
- Initial pump down to about 2E-2 mbar base pressure
- Maintain pressure (100-300 mbar, typically in a range of 100-130 mbar) while process gasses flow
- Low-pressure cleanup of diamond color after production
Nowadays, oil-sealed rotary vane pumps are typically used in the MPCVD process. This is because these pumps are very well suited to achieve low conditioning pressure but also because they are mainly designed for continuous operation at fine vacuum. Additionally, these pumps face poor lubrication, overheating, or high oil loss when operating for days in the rough pressure phase required by this process.
Advantages of oil sealed pumps
The oil lubrication of these vacuum pumps is secured by a built-in oil pump, which also enables a uniform oil distribution at rough pressure operation, whereas standard pumps without such oil pumps could fail.
Our range of rotary vane pumps is designed for operation at rough pressure and provides a perfect solution for the diverse pressure requirements of this growing process:
- The low ultimate pressure can easily meet the initial pump-down request, but the design of the pump also allows continuous operation at any (even rough) operation pressure
- Integrated high-efficiency exhaust filter that can reduce oil losses to the technical minimum. The oil stays inside the pump!
- Compact design. There is no need for an external exhaust oil mist separator with oil return
Browse Ash Air's range of vacuum pumps
The Ash Air range of rotary claw vacuum pumps is the best alternative to rotary vane pumps. A vacuum claw pump is virtually zero maintenance and compared to rotary vane pumps can work at vacuum levels of 400 to 1000 mbar without overheating. Rotary claw vacuum pumps are the best choice for CNC guided wood routers.
The Atlas Copco DZS series are mono claw, dry vacuum pumps that offer simplicity, robustness, efficiency and contaminant handling capability.
Atlas Copco vacuum pumps have always offered lower lifecycle costs, higher performance, less energy consumption and easy maintenance. Now, with the DZS VSD⁺ intelligent vacuum pump, you get that and much more. Think about intelligence, optimization, a plug & play pump, digitalization and a mobile app.
The Ash Air range of humble liquid ring pumps is still the most reliable form of large volume vacuum generation available today. These liquid ring pumps are simple to use and very reliable, and the best option when sucked air contains a large amount of saturated gas.
Pompetravaini liquid ring pumps have a low noise level and water flow, a stainless-steel impeller, reliable suction valves, and a compact installation. We offer Atlas Copco LRP VSD+ intelligent liquid ring vacuum offers superior vacuum performance and connectivity. It provides optimum energy efficiency along with low operational and maintenance costs. Its ease of use, integration into existing processes and centralization capabilities make this a truly unique liquid ring vacuum pump.
Contact us today to find out more about our range of liquid ring pumps.
Dry and oil-sealed vane vacuum pumps are robust, affordable and easy in maintenance. You can use DVP vane pumps for wide range of application, for skin packaging, holding, lifting, thermoforming.
We offer the Atlas Copco GVD series of 2-stage oil sealed rotary vane vacuum pumps deliver excellent ultimate vacuum pressure, high pumping speeds and superior vapor handling capabilities with quiet operation.
Also, the Atlas Copco GVS 16-630 A series operates according to the proven oil-sealed rotary vane principle that has been successfully used for many years in all general vacuum applications of industry packed with innovative features that ensure the highest possible performance at the lowest possible lifecycle cost.
At Ash Air we pride ourselves on supplying quality, reliable rotary vane vacuum pumps to our customers, with industry-leading servicing and spare parts for all brands. We offer 24/7 nationwide support with experienced engineers on hand to help when and where you need it.
We have a quality range of oil-sealed screw pumps for sale that are energy efficient and have low life-cycle costs.
The Atlas Copco GHS VSD⁺ series vacuum pumps are ideal for a range of applications in plastics, glass, bottling, canning, wood, packaging, printing and paper, meat packaging and many more. The GHS 350-900 VSD⁺ is the ideal solution when a dedicated pump is required in the production area. Atlas Copco GHS VSD⁺ is available in Turbo version for fast cycling and dedicated configuration and as well in Humid version with a greater water handling capability.
Contact the Ash Air team today for your screw vacuum pump needs.
Ash Air: Your one stop shop partner
With hundreds of years of combined experience and a broad product range, Ash Air is a great partner for your vacuum pump operations. From rotary vane pumps to screw pumps and accessories, we have a large variety of products. We also have a dedicated applications team ready to calculate the ideal pump configuration. With a global support organization, we can support your manufacturing operations wherever they may be located in New Zealand.
Ash Air has been around in New Zealand since 1979, and we’ve grown into a nationwide company with international support and a
reputation for quality and reliability.We look after all things compressed air for your business!
Ash Air's range of Chicago Pneumatic, Alup, Pneumatech, and Quincy compressors are used extensively around the world in industries
ranging from oil and gas to food, automotive and farming, and we bring you these world class compressors here in the land of the long white
cloud.Our technicians are compressed air equipment experts and are dedicated to addressing customer needs. Supported by a 13 locations
nationwide, Ash Air offers one of the widest selections of compressed air equipment and parts available today in New Zealand.
With Ash Air compressors, you can count on reliability and high performance for even the most demanding applications. We focus our
efforts on the following:
Talk to the team today: There are two types of vacuum pumps: the ‘wet’ kind, which is essentially a hydraulic pump, and the pneumatic, ‘dry’ variety.
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Ash Air has been around in New Zealand since 1979, and we’ve grown into a nationwide company with international support and a reputation for quality and reliability.We look after all things compressed air for your business!
Ash Air's range of Chicago Pneumatic, Alup, Pneumatech, and Quincy compressors are used extensively around the world in industries ranging from oil and gas to food, automotive and farming, and we bring you these world class compressors here in the land of the long white cloud.Our technicians are compressed air equipment experts and are dedicated to addressing customer needs. Supported by a 13 locations nationwide, Ash Air offers one of the widest selections of compressed air equipment and parts available today in New Zealand.
With Ash Air compressors, you can count on reliability and high performance for even the most demanding applications. We focus our efforts on the following:
Talk to the team today:
There are two types of vacuum pumps: the ‘wet’ kind, which is essentially a hydraulic pump, and the pneumatic, ‘dry’ variety. Read More…