Isostatic Graphite

How to Produce Isotropic Graphite

Fine fine-grain graphite manufacturing process adopts a unique molding process that gives the final product special features. A reason the final product is called special graphite or specialty graphite.

In most cases, the isostatic graphite manufacturers use nearly the same process in extruded graphite or vibration-molded graphite production. However, the difference comes in the molding stage.

Let’s look at the key stages in the isostatic graphite production process:

Preparing Raw Material

First, it is important to note that the isostatic molded graphite is an example of synthetic graphite. Therefore, you must choose carbon-based raw materials in their purest forms.

Remember, at the end of this process, every graphite manufacturer desires to get a material with 99.9999% purity.

Among the key primary raw materials in the graphite manufacturing process are:

• Coal or coke
• Binder pitch

Once you have all your raw materials in the right proportion, go ahead to mix and pulverize.

Usually, graphite raw material preparation involves a series of processes including kneading, pulverizing to sieving. The end product should be a homogenous mixture ready for the next process in the graphite manufacturing process.

At this stage, the process may follow different procedures. Some of the key stages include:

• Producing a paste after mixing raw materials
• Forming sheet with about 1 to 3 mm thickness
• Grinding the sheet into powder form

From here, you will transfer material to the mold for the isostatic pressing process.

Cold Isostatic Pressing (CIP) Process

Once you have raw material ready, it is the isostatic molding that makes the difference. Cold isostatic pressing is a unique processing technology that produces ultra-fine grain graphite with improved strength and thermal properties.

To produce isostatic graphite material, you will subject the mixture to a high compressive forces. That is, with the materials in the mold, isostatic pressing machine applies uniform pressure in all directions. The process refines the grains (fine structure) and ensures all desirable properties are uniformly distributed across the Isostatically molded graphite material.

Usually, the cold isostatic pressing graphite produces a highly isotropic material.

After cold isostatic pressing, it is now time to improve the intrinsic properties of the material through heat treatment.

Calcination with Optional Impregnation

After isostatic pressing graphite material, calcination and impregnation are other critical stages in the manufacturing process. Usually, the process improves the performance properties of graphite such as bulk density and strength.

Here, the process entails the following key stages:

• Fill containers with Isostatically molded graphite material
• Put the content in the calcination furnace
• At the same time impregnate graphite (For high-density graphite, impregnate 2 to 4 times)

Please note that after every impregnation cycle, you must subject graphite to the calcination process.

Usually, this is a slow process that can take many days. However, during the process, you must control critical parameters such as:

• The preheating temperature just before the calcination process begins
• Pressure
• Process time
• Vacuum

After subjecting Isostatically pressed graphite to this process, it is now time for graphitization.

Baking and Graphitization

It is important to note that throughout the first stages above, you were dealing with carbon material. Of course, every stage was preparing raw material to form isostatic graphite.

Therefore to convert carbon products into graphite, you will subject them to graphitization. That is, you will heat the product to a temperature of about 2500 to 3000 °C in a graphitization furnace.

Graphitization introduces a three-dimensional layered structure with a specific order. During the process, you may add Freon or chlorine gases to remove possible impurities.

Remember, graphite purification is critical. There are specific applications that require high-purity graphite of 99.9999%.

Once the process is complete, you will cool the isostatic graphite. Then go ahead to machine graphite to make other products such as graphite electrodes, bars, crucibles, etc.

Usually, the final products after the manufacturing process are available as Isostatically molded graphite rectangular blocks or round blocks. You can use these blocks for other processes.

Quality Inspection

Quality inspection is a fundamental process after the isostatic molding of graphite. It involves performing different tests including, compressive, density, Rockwell hardness, tensile strength, elastic modulus, and ash impurity test.

From these findings, the graphite manufacturer will then come up a technical data illustrating this finding. The data forms a fundamental aspect in grading graphite material.

Properties of Isostatically Pressed Graphite

Cold isostatic pressing produces graphite material with unique properties for specialized applications. Whether you are in the nuclear reactors, furnace production to EDM machining industry, you need a material with stable properties. A graphite material that guarantees optimal performance and reduces operational costs.

That’s exactly where Isostatically made graphite material comes in with unique properties:

Isotropic Structure

The conventional graphite materials available in the market have anisotropic structure. Therefore, conventional graphite materials do not have sufficient strength and density for certain applications.

That is where cold isostatic pressing graphite comes in handy. You will get graphite material with evenly distributed properties throughout the entire structure. A reason Isostatically pressed graphite is at times referred to as high-performance material.

High Density Material

One of the key properties of Isostatic graphite is its high density. Theoretically, the density may vary between 1.76 and 1.92 g/cm3 depending on the graphite grade.

Usually, isostatic graphite high density is attributed to the micro particle structure and the graphite manufacturing process.

Higher Strength

In case your application requires graphite with higher strength, the isostatic pressing offers a perfect option. The micro-structure offers higher mechanical strength which varies depending on the graphite grade.

Improved Electrical Conductivity

If you are looking for a perfect material for high-temperature heaters, then choose isostatic pressed graphite. CIP produces graphite material with higher heat resistance, which is perfect for most industrial heating systems.

Superior Heat Resistance

Isostatic molded graphite can withstand extremely high temperatures (up to 2,000℃). Its isotropic structure will guarantee exceptional thermal performance such as:

• High coefficient of thermal conductivity
• Low thermal expansion
• Superior thermal shock
• Low thermal deformation
• Uniform heat distribution

All these make isostatic molded graphite perfect for most industrial applications. Additionally, this graphite exhibits better strength with an increase in temperature.

Easily Machinable Graphite

Whether you want to make custom graphite parts or intricate components, the material has good machining properties. Isostatic graphite machining is not different from conventional graphite materials.

You can use the normal graphite machining operations such as:

• Milling graphite
• Drilling graphite
• Turning graphite
• Electrical discharge machining graphite

Better Chemical Resistance

Chemical resistance is one of the isostatic graphite properties, which makes the material popular across many industries. Apart from the compressive strength of isostatic molded graphite, it is not affected by most chemicals. The material is virtually inert.

Low Impurity

As a specialized material, it has low impurities. In most cases, most grades have < 5 ppm.

Remember, the need for 99.9999% purity is becoming a priority in the semiconductor manufacturing industry. Therefore, for isostatic pressing, you need high-purity graphite to achieve a fine-grain material with superior performance.

Isostatically Molded Graphite Grades

Depending on the application requirements, you can choose a wide range of isostatic graphite material grades. Each grade is uniquely customized to have specific properties.

However, you should note that there are no universally recognized grades. Every isostatic graphite manufacturer can classify graphite material depending on their material composition.

Here is a table with various parameters to help you choose a perfect material grade:

Note: The grade in the table above is an arbitrary number. Once the manufacturer knows your intended application, they will recommend a specific graphite material grade.

Key Applications of Isostatically Molded Graphite

You can machine Isostatically molded graphite materials to make many parts or components. Remember, the stock materials are available as high-purity isostatic graphite blocks or isostatic graphite rods.

As specially molded graphite material, you can use it in many industries such as:

Furnace Parts

Isostatic graphite furnace parts such as crucibles, rings, tubes, bolts, fasteners, shields, hot zone elements, and insulation materials that can withstand extreme heat. Furthermore, isostatic graphite electrodes are important components of electric arc furnaces.

Electronics Industry

Among the key industries that benefit from Isostatically molded graphite is the semi-conductor.  Where graphite plays an integral role in the silicon wafer manufacturing process.

Besides, you can use it for isostatic casting mold, parts in the thermal field, to precision circuit boards.

Foundry and Fabrication Shops

Whether in copper continuous casting or melting rare metals in a graphite crucible, Isostatically pressed graphite reduces your production costs and improves part production.

Furthermore, you can use the material in sintering mold and hard alloy processing.

From single crystal furnaces to metal continuous casting process, fine-grade and high-density graphite offers the perfect manufacturing solution.

Precision Machining

Graphite electrodes are fundamental parts of the electrical discharge machining process (EDM). The electrodes guarantee precise part machining.

As a matter of fact, graphite electrodes have revolutionized the electrical spark discharge machining industry.

Material Analysis in Laboratories

Isostatic graphite products are widely used in many laboratory analysis projects.  Being a virtually inert and heat-resistant material, you can use this material in graphite boat, mold, dish, or container manufacturing.

Nuclear Industry

Have you come across the term nuclear graphite? Well, these are mainly Isostatically molded graphite that acts as moderators and neuron reflectors in nuclear reactors.

Solar Power Systems

The high demand for polycrystalline and single-crystal silicon in the solar industry makes graphite a perfect solution for the manufacturing process. In fact, the unique properties of isostatic graphite make it a viable option due to its high strength and purity.

In addition to the above applications, others include graphite brushes, seals, collector plates, sintering molds, cutting tools, heating systems, piston rings, rocket nozzles, and bearings, just to mention a few.

East Carbon – Your Trusted Isostatic Graphite Manufacturer in China

Are you looking for a trusted China isostatic graphite manufacturer? East Carbon is a partner with rich experience in high-performance graphite materials. With years of experience in Isostatically molded graphite, we produce different graphite material grades with varying specifications.

We ensure consistent quality in every synthetic graphite, by subjecting each material to rigorous testing. Whether you want graphite with 99.9999% purity, East Carbon is always up to the task.

With isotropic structure, ultrafine particles, and high mechanical strength Eastcarb graphite meets the dynamic needs of industrial applications. Share your project details now and we will supply high-quality isostatic molded graphite.

For any inquiries, contact us now.

FAQs

Is Vibratory Molded Graphite better than Isostatic Molded Graphite?

It will depend on where you want to use the graphite material.

Generally, the isostatic molded graphite materials are suitable for specialized applications. This is due to high density, high strength, and fine grain.

On the other hand, vibration molding produces graphite with a coarse structure. The particle size varies from 0.5 to 2mm.

What is the Difference between Isostatic and Extruded Graphite?

Unlike isostatic graphite where you will use cold isostatic pressing (CIP), to produce extruded graphite, you will use the extrusion process.

Furthermore, Isostatically molded graphite has the finest grain structure. The fine grain makes it a popular synthetic graphite for specialized applications.

On the other hand, extruded graphite has a coarse grain structure.

How big is the Isostatic Graphite Market?

Due to the specialized nature of Isostatically manufactured graphite, the demand continues to grow over the years. Among the main industries that continue to spur this growth is the semi-conductor.

Currently, there is a high demand for semi-conductor products, precise machining like EDM, and processing rare materials. All these contribute to exponential growth in the Isostatically compressed graphite market.

Unlike 2020 when the isostatic graphite market grew by 3.5%, this year, it may surpass 8.3%.  But more importantly, by 2028, you should expect the isostatic graphite market to be over 2 billion USD.

Of course, this growth will also affect the isostatic graphite block price. Currently, the price of isostatic graphite is about 7 USD to 15 USD per kilogram.

If you are looking for competitive graphite material prices, East Carbon is your trusted graphite manufacturer in China.

Are there CE Certified Isostatic Graphite?

Yes, CE is a standard certification that ensures graphite meets the specified quality standards. CE certification on isostatic graphite is critical, especially for sensitive applications such as nuclear reactors and furnaces.