CS251462B1 - Method of powder compacting - Google Patents

Abstract

The solution relates to a method of compacting metal, metal ceramic and ceramic powders. The essence of the solution is that during compacting and sintering phases are compacted the powder acts by ultrasonic v frequency range of 15 to 213 kHz. solution can be used in steel and ceramic industry.

Description

The invention relates to the compacting of metal, metal-ceramic and ceramic powders.

Until now, compacting of powders is accomplished by pressing, rolling and forging and subsequent sintering at temperatures above the recrystallization temperature of the material without further affecting the sintered materials. All previous processes are suitable for products of smaller dimensions, because with the increase in the height of the product, the pressure drop due to the friction of the powder against the tool walls is adversely affected. The occurrence and existence of defects is observed in the products, which in many cases leads to a deterioration of their mechanical and physical properties. Hitherto known methods achieve a density of the material in the range of 99.15 to 99.50% of the compacted material, and the internal stresses are in the range of 100 to 200 MPa.

The above drawbacks are overcome by the method of compacting the powders according to the invention, which is characterized in that during the compaction and sintering phase, the compacted powders are subjected to ultrasonic treatment in the frequency range of 15 to 213 kHz. When the ultrasound is applied in the pulse mode, the pulse duration is 1 to 200, us and the pulse repetition frequency is 1 to 1000 Hz.

The method of compacting the powders of the invention improves the arrangement of the powder into a denser state, thereby reducing or eliminating pore, void, bubble and other imperfection defects. The diffusion conditions and hence the mechanical and physical properties of the product are improved. The material density of the products obtained in this way is increased to 99.65 to 99.99% of the compacted material, the internal stresses are reduced to 30 to 0 MPa and the compacting time is reduced by 20%.

Example 1

Steel with a chemical composition of 0.86% by weight % of carbon, 5.67 wt. % molybdenum, 6.82 wt. % tungsten, 4.19 wt. % chromium, 1.62 wt. % vanadium, 0.42 wt. % manganese, 0.12 wt. % silicon and 0.026 wt. Sulfur was pressed at 200 MPa at 1250 ° C. After compression, a specific gravity of 98.6% was found.

After the application of ultrasonic energy to the system in the process of compacting with a 17.5 kHz ultrasonic frequency, the specific gravity of the material was 99.65%. Example 2

The chemical composition steel as in Example 1 was isostatically pressed for 60 minutes at a temperature of 1250 ° C and a pressure of 200 MPa. The resulting specific gravity reached 99.50%.

After the application of ultrasonic energy by the pulsed ultrasonic generator in the process of compacting at the following ultrasonic pole values: frequency 20 kHz, repetitive frequency 150 Hz, pulse width 35 µs, a specific gravity of 99.99% per second was achieved.

Claims (2)

PEEDMET Method for compacting powders, characterized in that during the compaction phase and the sintering phase, the compacted powders are subjected to ultrasonic treatment in the frequency range of 15 to 213 kHz. We claim: 2. Method according to claim 1, characterized in that the compacted powders are subjected to a pulse mode ultrasound with a pulse duration of 1 to 200 μβ and a repeated pulse frequency of 1 to 1000 Hz.