CS251462B1 - The method of powdering powders - Google Patents

Abstract

The solution concerns a method of compacting metal, cermet and ceramic powders. The essence of the solution is that during the compaction and sintering phase, the compacted powder is treated with ultrasound in the frequency range of 15 to 213 kHz. The solution can be used in the steel and ceramic industries.

Description

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

So far, the compacting of powders has been effected by compression, rolling and forging and subsequent sintering at temperatures above the material's recrystallization temperature without further affecting the sintered materials. All prior art 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 to the tool walls is adversely affected. In products, the formation and existence of defects is observed, which in many cases leads to a deterioration of their mechanical and physical properties. To date, the density of the material in the range of 99.15 to 99.50% of the compacted material is achieved and the internal stresses are in the range of 100 to 200 MPa.

The aforementioned drawbacks are eliminated by the method of compacting the powders according to the invention, wherein ultrasound is applied to the compacted powders in the frequency range of 15 to 213 kHz during compacting and sintering phases. With ultrasound in pulse mode, the pulse duration is 1 to 200 με and the pulse repetition frequency is 1 to 1,000 Hz.

The method of compacting the powders of the invention improves the configuration of the powder to a denser state, thereby reducing or completely eliminating defects such as pores, cavities, bubbles and other imperfections. The diffusion conditions and thus the mechanical and physical properties of the product will be 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

Chemical composition 0.86 wt. % carbon, 5.67 wt. % molybdenum, 6.82 wt. tungsten, 4.19 wt. of chromium, 1.62 percent by weight; % vanadium, 0.42 wt. % of manganese, 0.12 wt. % silicon and 0.026 wt. sulfur was compressed at 200 MPa at a temperature of 1250 ° C. A specific gravity of 98.6% was determined after compression.

After application of ultrasonic energy to the system in the process of compacting with the UZ of 17.5 kHz, the material density was 99.65%.

Example 2

The chemical composition of Example 1 was isostatically pressed for 60 minutes at 1250 ° C and 200 MPa. The resulting specific gravity was 99.50%.

After the ultrasonic energy is applied by the pulsed ultrasonic generator in the compacting process with the following ultrasonic field values: frequency 20 kHz, repetition frequency 150 Hz, pulse width 35 με, specific gravity 99.99 ° / o.

Claims (2)

SUBJECT OF THE INVENTION A method for compacting powders, characterized in that during compacting phase and sintering phase, the compacted powders are sonicated at a frequency range of 15 to 213 kHz. 2. The method of claim 1 wherein the compacted powders are ultrasonically pulsed with a pulse duration of 1 to 200 and a pulse repetition rate of 1 to 1000 Hz.