SU1614898A1 - Method of applying diffusion coatings on metallic powders - Google Patents

Abstract

The invention relates to powder metallurgy, in particular to methods for coating metal powders. The purpose of the invention is to shorten the process time and improve the quality of the coating. To achieve the goal, the mixture of metal powder, alloying agent and activator is subjected to vacuuming, heating, isothermal exposure and cooling when applying vibration with a frequency of F ₁ = 8 + 0.075 D _cf and amplitude A = (1200-2400) / F ₁ for isothermal holding and with frequency F ₂ = 1.5F ₁ and amplitude A ₂ = (800-1000) / F ₂ , where F ₁ and F ₂ - vibration frequency, Hz

A ₁ and A ₂ - amplitude, mm

D _cf - the average particle diameter of the metal powder, microns. In this case, borated, aluminized, chrome-plated and other metal powders with uniform coating are obtained, with a significant reduction in the duration of the process. 2 tab.

Description

The invention relates to powder metallurgy, in particular to methods for coating metal powders.

The purpose of the invention is to reduce the length. process and quality improvement of the coating.

The essence of the proposed method is as follows.

Aluminum and boron carbide powder are chosen as applied alloying elements. The coating is applied to a powder of pure iron of various fractions, which are obtained by sifting out a powder of the PRZH brand, the shape of particles is spherical.

To create a halogen medium in the container, the activator powder and AlClg are added to the mixture of powders of pure iron (97 wt.%) And doping additive (3 wt.%) And the powder mixture is evacuated with a backing pump up to 10 mm Hg.

The coating process is carried out in three stages.

1-stage. Heating to 900 ° C, shutdown of the vacuum pump. Heating time 1h.

2-stage. The isotheric holding time is 20 min, the activator vapor pressure is 0.9-1.5 atm. The activator decomposes to form the subchloride doped

00

with

00

Fschs additives that react with carbon dioxide, release aluminum atoms of boron ifi, diffusing into the IIHH product to form solid solutions of iron based on iron or compounds (boids, intermetallic compounds). I 3-stage. Cooling to 400 ° C; 1x to under vacuum. Art. they take out. During the entire coating process, vibration is applied to the container. G In table. Figure 1 shows the results of the influence of the frequency and amplitude of the vibration during the heating and cooling stages. I In tab. Figure 2 shows experimental data on the effect of vibration mode at the stage of isothermal exposure on the quality of the recorded surface. The duration of the saturation process is 20 minutes, the temperature is 870 C, the ratio of the height of the layer of the mixture in the container to the diameter of the container (1-2) 51, the average particle size of the powder of the proposed method of applying diffusion coatings to metal powders provides a reduction in the time of coating in more than 10 times the decline

Quality of applied coating by

improving the uniformity of saturation of the poropps surface with the dopant, as well as by eliminating sintering of the powder particles and changing their original shape.

Claims (1)

Invention Formula The method of applying diffusion coatings to metal powders, including the evacuation of a mixture of a mixture of a metal of a dopant and an activator, heating, isothermal holding and cooling, is necessary in order to reduce the duration of the process and improving the quality of the coating, the isothermal expansion is carried out with (vibration overlays with a frequency of f 8 + 0.075 Dcp and amplitude Ajj (1200-2400) /, where f is the vibration frequency, Hz; D (.p is the average particle diameter of the metal powder, µm} A - the amplitude of vibration, mm, and heating and cooling is carried out under vibration with a frequency of fa - J and amplitude Aj, (800-1000) / f |, where f is the frequency of vibration in Hz;.. A2 - vibration amplitude mm. Table 1 1 Heating and cooling without vibrations 2 ten 18 20 without Powder Baking Powder Partially Baking Same thing Powder Baking Powder Partially Baking Powder caking Individual lumps Powder does not bake Same 1 Altirovanie Chrome-plated Borivirovanna 8 Altiming Chrome plating Boring 10 Alitizing Continuation of table 1 it is speciously baked Powder partially coking table 2 1614898 editor A, Kozorie Compiled by, Sekrvdova Tehred M. Khodanich Proofreader C, Shevkun Order 39D7 Circulation 638 VNIIGSH of the State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 4/5, Moscow, Zh-35, Raushsk nab. 113035 Production and publishing plant Patent, Uzhgorod, st. Gagarin, 101 eight Continuation of table 2 Subscription