RU1789570C - Method of producing high purity titanium - Google Patents

Abstract

Usage: obtaining titanium of high purity by refining electron beam melting. Essence: titanium is melted in an electron-beam installation with an electron beam power of 0.5-0.8 kW / cm2 at a rate of 6-8 mm / min of residual gases no more than 1 mm Hg. Art. and leakage not higher than 0.1 l μm / s. 1 tab.

Description

The invention relates to titanium metallurgy, and in particular to methods for producing high purity titanium.

A known method for producing high-purity titanium, including electron beam melting of electrolytic titanium at a residual gas pressure of 1-m bar (High-purity titanium sputtering targets for VLSIS. Catalog of the company Vacuum Metallurgical Co Ltd, 1988). Titanium obtained by this method is characterized by: an oxygen content of 60 ppm; hydrogen 20 ppm; nitrogen 3 ppm; iron, nickel, chromium no more than 5 ppm each; sodium and potassium not more than 0.1 ppm; a hardness of 84 kg / mm and an electrical resistance ratio of 85.

The prototype of the invention is a method for producing high-purity titanium by electron beam melting of initial titanium containing 100-160 pounds of oxygen, not more than 10 pounds of iron, not more than 18 pounds of chromium, 1 ppm of nickel, 325 pounds of sodium, 175 pounds of potassium 1.

Melting is carried out at an electron beam power of 20-30 kW at a speed of 2 kg / h with a residual gas pressure in the working volume of 3.7 mm Hg. Art.

The material obtained by this method contains 100-150 ppm of oxygen; 0.4-0.8 pounds of iron; 0.3-0.5 ppm of chromium; 0.1-0.3 ppm nickel, not more than 0.05 ppm K and Na. The hardness of the resulting material is about 80 kg / mm.

In this case, the ratio of electrical resistance fluctuates in the range of 55-75.

The aim of the invention is to improve the quality of titanium by increasing the ratio of electrical resistance

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The goal is achieved in that in the proposed method, titanium refining is carried out in an electron beam installation with an electron beam power of 0.5-0.8 kW / cm2 at a speed of 6-8 mm / min and a residual gas pressure of not more than 1 10 mm Hg. Art. and leakage no higher than 0.1 l.min / s.

The found melting parameters provide obtaining higher quality material with improved electrical resistance ratio (OSS according to prototype 55-75, OOS according to the claimed method 90-150). This is due to the fact that the claimed parameters increase the degree of purification of the initial titanium from alkali metals to 0.01 ppm; from aluminum to 10 ppm; calcium, magnesium, manganese up to 0.01 ppm.

In addition, the limitation of the values of the run and pressure of the residual gases in the working volume makes it possible to conduct electron beam melting at a partial pressure of oxygen and carbon-containing gases of not more than 1 mm Hg. Art. (each), and nitrogen-containing - not more than 1 mm RT. Art., which allows you to leave at the initial level the concentration of oxygen, carbon, nitrogen and increase the ratio of electrical resistance of the OOS from 75 to 90-120.

Justification of the modes. An electron beam melting wire of a material with a speed exceeding 8 mm / min or with an electron beam power of less than 0.5 kW / cm produces ingots with an electrical resistance ratio of less than 20 due to inclusions of unmelted metal and a high concentration of metallic impurities.

If the electron beam power exceeds 0.8 kW / cm2, or titanium melts at a rate of less than b mm / min, then ingots are significantly contaminated with interstitial impurities - the total concentration of which reaches 2000 ppm.

The ratio of electrical resistivity in such ingots also does not exceed 20 units. This is apparently associated with an increase in the contact time of the residual gases with the melt due to an increase in the melt pool and a significant decrease in the rate of crystallization of the metal; in addition, overheating of the metal also leads to increased evaporation of titanium and, therefore, enrichment of it with impurities of non-volatile elements.

Pressure increase over 5 mmHg. Art. or leakage above 0.1 l / mm during smelting significantly increases the partial pressure of gases in the atmosphere of the working volume, and therefore leads to an increase in the concentration of oxygen, carbon, nitrogen in the ingot and a decrease in the value of the OOS electrical resistance ratio.

Example 1. Titanium containing: 0-100-160 ppm; N 5-8 rt; With 10 ppm; Fe 3-9 ppm; СГЗ-б ррт; A1100 ppm; Ca 30 ppm; MD 10 ppm; MP 400 rt; Mi 0.4 ppm; Na 400 ppm; With 0.4 ppm; K - 500 ppm; loaded into an electron beam furnace. Melting modes: Power of an electron beam (N) 0.6 kW / cm2;

Melting speed (V) 7 mm / min; Residual gas pressure in the working

volume (Height) 5 mm RT. st .;

Leakage into the working volume of 0.1 lmin / s.

After melting according to the above modes, the obtained titanium ingot has: OOS 90; hardness 60 mg / mm2; and contains: 0-100-1§0 ppm; N 5-8 rt; With 10 ppm; Fe 3-9 ppm; Cr 3-5 ppm; AI 10 ppm; Ca 0.05 ppm; Mp 0.1 ppm:, 01 ppm: Ni 0.4 ppm: CoO, 04 ppm,, 04 ppm: K 0.03 ppm.

Smelting conditions and OOS values for Examples 2-11 are shown in the table.

Thus, the claimed method allows to obtain titanium having high electrophysical properties with OOS 100 (prototype no more than 75).

Such a material can be used to make magnetron sputtering targets.

The method can be implemented on standard equipment manufactured in the country.

Claims (1)

Formula invented and A method for producing high-purity titanium, including refining by electron beam melting, characterized in that, in order to improve the quality of the metal by improving the electrophysical properties, melting is carried out at an electron beam power of 0.5-0.8 kW / cm2 and a speed of 6- 8 mm / min at a pressure of residual gases in the working volume of not more than 1 mm RT. Art. and leaks not higher than 0.1 l μm / s.