PRODUCT CATEGORIES

Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

Vacuum sintered powder metallurgy parts

Powder metallurgy is an important part forming technology. The continuous emergence of new technologies and processes of powder metallurgy will surely promote the rapid development of high-tech industries, and will also bring bright prospects for material engineering and manufacturing technology. Powder metallurgy vacuum sintering is a method and technology for strengthening and densifying products by heating powder or powder compacts in a vacuum. Vacuum sintering is the most important process in the powder metallurgy process. During the vacuum sintering process, physical and chemical changes such as bonding occur between powder compact particles due to temperature changes, thereby increasing the resistivity, strength, hardness and density of vacuum sintered products, reducing porosity and making the grain structure densification.

Basic composition of vacuum sintering furnace

Powder metallurgy vacuum sintering furnace generally consists of three parts: preheating zone, vacuum sintering zone and cooling zone. Their functions are as follows:

1.Preheating zone: preheating powder compact and burning off lubricant;

2.Vacuum sintering belt: keep the green compact at a specified temperature for a long enough time to obtain the physical-mechanical properties required for vacuum sintering parts;

3.Cooling zone: including pre-cooling zone and water jacket cooling zone. The compact is cooled slowly from high temperature to recrystallization temperature and then rapidly cooled to obtain the final microstructure of the product.

Classification method of powder metallurgy vacuum sintering

In powder metallurgy, different products and different performance vacuum sintering methods are different.

(1) Classified according to the composition of raw materials. Vacuum sintering can be divided into unit-based vacuum sintering, multi-component solid-phase vacuum sintering and multi-component liquid-phase vacuum sintering.

The vacuum sintering of the unit system is a solid phase vacuum sintering at a temperature below the melting point of pure metals (such as refractory metals and pure iron soft magnetic materials) or compounds (Al₂O₃, B₄C, BeO, MoSi₂, etc.). The multi-component solid-phase vacuum sintering is a vacuum sintering system composed of two or more components, and the solid-phase vacuum sintering is carried out below the melting point temperature of the low-melting component. Powder vacuum sintered alloys mostly belong to this category. Such as Cu-Ni, Fe-Ni, Cu-Au, W-Mo, Ag-Au, Fe-Cu, W-Ni, Fe-C, Cu-C, Cu-W, Ag-W, etc. Multi-system liquid-phase vacuum sintering is vacuum sintering performed at a temperature exceeding the melting point of the low-melting components in the system. Such as W-Cu-Ni, W-C powder metallurgy u, WC-Co, TiC-Ni, Fe-Cu (Cu>10%, Fe-Ni-Al, Cu-Pb, Cu-Sn, Fe-Cu (Cu<10 %)wait.

⑵Classified according to different feeding methods. Divided into continuous vacuum sintering and intermittent vacuum sintering.

Continuous vacuum sintering The vacuum sintering furnace has various functional sections of dewaxing, pre-sintering, vacuum sintering, and refrigeration. During vacuum sintering, the vacuum sintering material completes the vacuum sintering of each stage continuously or smoothly and in sections. Continuous vacuum sintering has high production efficiency and is suitable for mass production. Commonly used feeding methods include push rod type, roller table type and mesh belt transmission type.

The intermittent vacuum sintering parts are placed in the furnace still, and the required preheating, heating and cooling cycle operations are performed on the vacuum sintering furnace through the temperature control equipment to complete the vacuum sintering process of the vacuum sintering material. Intermittent vacuum sintering can determine the appropriate vacuum sintering system according to the performance of the vacuum sintering material in the furnace, but the production efficiency is low, and it is suitable for single piece and small batch production. The commonly used vacuum sintering furnaces include bell jar furnaces and box furnaces.

In addition to the above classification methods. According to whether there is a liquid phase at the vacuum sintering temperature, it is divided into solid-phase vacuum sintering and liquid-phase vacuum sintering; according to the vacuum sintering temperature, it is divided into medium-temperature vacuum sintering and high-temperature vacuum sintering (1100-1700 ° C), and according to the vacuum sintering atmosphere It is divided into air Vacuum sintering, hydrogen protection vacuum sintering (such as molybdenum wire furnace, stainless steel tube and hydrogen furnace, etc.). In addition, there are new vacuum sintering technologies such as ultra-high pressure vacuum sintering and activated hot-pressing vacuum sintering.

Factors Affecting Vacuum Sintering of Powder Metallurgy Parts

1.The properties of materials, including various interface energies and free energies: diffusion coefficient, viscosity coefficient, critical shear stress, vapor pressure and evaporation rate, lattice type and crystal form, new ecology of heteromorphic transformation, etc.

2.The nature of the powder: including particle size; particle shape and morphology; particle structure; particle chemical composition.

3.The physical properties of the compact: including compaction density, compaction residual stress, deformation or destruction of the oxide film on the particle surface, and gas in the pores of the compact, etc.

4.Vacuum sintering process parameters: including holding time, heating and cooling speed, vacuum sintering atmosphere, etc.