Introduciton of Hot pressing
Hot pressing is a manufacturing process that involves the application of heat and pressure to a material to create a dense and uniform product. This process is commonly used in the production of ceramics, composites, and metals. The hot pressing process involves placing the material in a mold and then heating it to a high temperature while applying pressure. The heat and pressure cause the material to soften and flow, filling the mold and creating a dense and uniform product.
Introduction of SPS
Spark Plasma Sintering (SPS), is a new type of new sintering technology developed in recent years. Spark Plasma Sintering (SPS) of the powders is one of promising methods of fabricating the high-density fine-grained ceramics, metallic and hard alloys. SPS is an improved method of hot pressing. SPS technology consists of rapidly heating and electrically conductive mold filled with powder or green body by passing millisecond pulses of electric current while simultaneously applying a uniaxial load. The load is applied by placing the mold between the press plungers. The sintering is performed in a vacuum or in an inert atmosphere.
The use of the pulsed mode allows heating the powder with a high speed. It allows reducing the sintering time and preserving the grain sizes in the sintered samples close to the particle sizes in the initial powder.
At present, SPS is one of the efficient methods for fabricating the metallic and ceramic materials with high density and improved mechanical properties or performance characteristics. Using SPS technology, different metallic materials such as titanium, tungsten, copper, and other alloys, as well as the ceramic materials like Al2O3, Si3N4, WC, and MgAl2O4 can be produced. Besides, thermoelectric materials, transparent ceramics, functionally gradient materials, and coatings, are fabricated using SPS.
Graphite Mold for SPS
Typically, SPS is performed using a graphite mold, which is a hollow cylinder with an inner diameter ranging from 10 to 200 mm. The mold is mounted vertically inside the chamber. The powder inside the mold is supported from the top and from the bottom by two graphite punches. A graphite foil of several hundred microns in thickness is used to minimize the gap between the sample and the inner surface of the mold. Both punches are wrapped in the graphite foil. Also, the graphite foil or graphite pads of several millimeters in height are placed between the punches and the powder. This way, the powder to be sintered contacts the graphite parts directly at all sides.
Graphite is ideal material for making the molds, punches, and the foil. The use of graphite as the material for molds and punches is caused by its high electrical and thermal conductivity, heat capacity, high melting point, high strength, chemical resistance in aggressive media, low cost, and easy processing. The requirements of high electrical and thermal conductivity are imposed also on the graphite foil.
Benefits
- Excellent Surface finish
- Increased lifetime
- High density component output
- Uniform distribution leads to uniform end products
- Exceptional release characteristics
- Maintains press through thermal cycle
Technical Data of Graphite Material:
Isostatic Graphite
| Property |
KBD-5 |
KBD-6 |
KBD-7 |
KBD-7B |
KBD-8 |
Unit |
| Apparent Density |
1.85 |
1.90 |
1.82 |
1.82 |
1.90 |
g/cm3 |
| Max Grain Size |
13-15 |
8-10 |
8-10 |
13-15 |
8-10 |
µm |
| Ash value |
≤500 |
≤500 |
≤500 |
≤500 |
≤500 |
ppm |
| Specific Electrical Resistivity |
8-10 |
8-9 |
11-13 |
11-13 |
11-13 |
μΩm |
| Flexural Strength |
46 |
55 |
51 |
59 |
60 |
Mpa |
| Compressive Strength |
85 |
95 |
115 |
121 |
135 |
Mpa |
| Shore Hardness |
48 |
53 |
65 |
70 |
70 |
HSD |
| Thermal Expansion (room temperature to 600ºC) |
4.75 |
4.8 |
5.8 |
5.8 |
5.85 |
10-6/ºC |
Molded Graphite
| Property |
KBG-4 |
KBG-5 |
Unit |
| Apparent Density |
≥1.80 |
≥1.85 |
g/cm3 |
| Ash value |
≤500 |
≤500 |
ppm |
| Shore Hardness |
≥40 |
≥45 |
HSD |
| Specific Electrical Resistivity |
≤12 |
≤12 |
μΩm |
| Flexural Strength |
38 |
41 |
Mpa |
| Compressive Strength |
81 |
87 |
Mpa |
| Max Grain Size |
25 |
25 |
μm |
Vibration Graphite
| Property |
TSK |
GSK |
Unit |
| Apparent Density |
≥1.70 |
≥1.72 |
g/cm3 |
| Max Grain Size |
≤2 |
≤0.8 |
mm |
| Specific Electrical Resistivity |
8-10 |
≤8.5 |
μΩm |
| Flexural Strength |
≥12.5 |
≥15 |
Mpa |
| Compressive Strength |
≥28 |
≥35 |
Mpa |
| Porosity |
≤24 |
≤20 |
% |
| Ash value |
≤0.3 |
≤0.3 |
% |
Advanced Production Equipment
Strict Quality Control Ensures High Quality Products
Safe Packing
Question and Answer:
Q:Are you a manufacturer or trading company?
A:We are a manufacture for graphite material and graphite machined products.
Q:How can you gurantee the quality?
A:We have the most advanced equipments in our Lab and professional quality control team.We can gurantee each batch of the product with the stable quality.
Q:Can you offer samples?
A: Yes, we offer samples to test
Q: Delivery time?
A:Around 10 days.
Q: Shipping pot
A: Tianjin or main port in China
Q:Payment terms
A:T/T,LC at sight
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