DE1217184B - Process for the production of ductile metals in finely divided form - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

B 02c

German KL: SOc-17/40

Number: 1217 184

File number: N 20050 HI / 50 c

Filing date: May 15, 1961

Opening day: May 18, 1966

Milling process for the production of fine metal powder are known. Difficulties can arise in this process when pulverizing ductile metals Need to become. It has already been suggested that such metals be given a to give a certain brittleness. For this purpose, z. B. increases the carbon content of iron or nitration is carried out. After the grinding process, the resulting powder can be oxygenated can be freed by reduction using hydrogen at elevated temperature. The reduced product is then crushed and sifted.

The invention relates to a method for producing a finely divided powder from a ductile one Metals such as tantalum, niobium, vanadium, titanium and zirconium, which are exothermic trapping hydrogens Metals can be designated.

The metals mentioned form good getter materials in finely divided form which, for. B. in discharge tubes Can find application.

For non-evaporating getter materials, the size of the surface area of the material is more critical Importance. As the surface area increases, not only does the getter capacity decrease, but also the getter speed increases.

Most of the metals which are well suited as non-evaporating getters due to their chemical properties, such as B. Ta, Nb, V, Ti and Zr, are often very ductile. You are therefore by simple Do not bring grinding into a fine powdery form.

The invention aims to overcome the difficulties. Then there is the manufacturing process a finely divided powder made of a ductile metal such as tantalum, niobium, vanadium, titanium or zirconium, by grinding a brittle compound, e.g. B. the hydride of the metal, in that according to the invention the milling process is done in an atmosphere of pure hydrogen to during of the grinding to form a hydride, which after the grinding process by heating in a vacuum Hydrogen is withdrawn again.

The reasons for the fine grain of the resulting ground product are probably as follows: First of all, oxide-free metal surfaces are created in places by mechanical action during grinding. These clean areas of the metals react with the surrounding hydrogen to form hydride phases on the surface. The formation of hydrides, especially in the case of Ta, Nb, V, Ti and Zr, takes place with a considerable increase in volume, as a result of which strong stresses at the interface between the hydride phases and the base metal result in the production of ductile ones
Metals in finely divided form

Applicant:

N. V. Philips' Gloeilampenfabrieken,

Eindhoven (Netherlands)

Representative:

Dr. rer. nat. P. Roßbach, patent attorney,

Hamburg 1, Mönckebergstr. 7th

Named as inventor:

Dipl.-Chem. Dr. Karl Georg Knauff, Aachen - -

stand. The increase in volume is usually around 10 to 20%. Furthermore, the hydrides are these Metals mechanically very brittle. The state of tension on the surface and the embrittlement lead now together with the mechanical stress during the grinding process to a detachment of the finest Metal hydride particles from the surface, after which the process repeats itself until the entire Metal is converted into hydride and is now in extremely fine form.

By heating in a vacuum, which is useful in the manufacture of discharge tubes after attachment of the hydride can take place on the electrodes, the hydrides can contain all of the hydrogen can be withdrawn again, and the pure metal is now obtained in a once-distributed state.

The grinding process is expediently carried out in a steel vibrating ball mill which is sealed gas-tight executed. The pure hydrogen required can be supplied through a hose made of, for. B. diffusion-proof Butyl rubber are supplied.

The process has proven itself particularly with titanium and zirconium.

When zirconium was ground in this way for about 1 hour, a powder with a surface area of 5.5 m ² / g was obtained after heating in vacuo to 500 ° C.

Claims (1)

Claim: Process for the production of a finely divided powder from a ductile metal such as tantalum, 609 569/238 3 4 Niobium, vanadium, titanium or zirconium, by grinding after the grinding process by heating in the va- len a brittle compound, e.g. B. the hydride kuum the hydrogen is withdrawn again. of the metal, characterized that the grinding process in an atmosphere of pure hydrogen is made in order to select 5 Publications considered: to form a hydride upon milling, British Patent No. 671,664. 609 S69 / 238 5.66 © Bundesdruckerei Berlin