DD157868A3 - PROCESS FOR PREPARING NBZR 1 - Google Patents

Abstract

A process for the production of semifinished product from NbZr 1, which has specific mechanical properties and serves as a component for closing the discharge vessels in the production of high-pressure sodium lamps. The invention is based on the object to produce the alloy NbZr 1 by a single remelting in the electron beam multi-chamber furnace and thereby To achieve a high consistency of Zr concentration over the cross section of the molten ingot. According to the invention this is achieved in that Abschmelzstaebe be prepared from the pure metals corresponding to Figure 1 or Figure 2 and melted in the electron beam multi-chamber furnace under specific conditions to strand material diameter 60 mm.

Description

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Process for the production of semifinished products from NbZi? T

To-use un the invention gsgebiet

Di6 invention relates to a method for producing semifinished products, in particular strip material, of the alloy NbZr1 with. specific mechanical properties for use as a device for sealing the discharge vessels in the production of high pressure sodium vapor lamps.

Characteristic of the known technical solutions

The two alloying metals niobium and zirconium belong to the group of refractory reactive metals, in which the possibilities of alloying processes are not unlimited, since vacua of at least 5 x 10 torr must be assumed. The temperatures required for melting can be generated only in the arc or electron beam furnace. The difficulty in using these melting and alloying processes is that due to the discontinuous mode of operation and the very different vapor pressures of the pure metals, no homogeneous distribution of the zirconium in the Nb matrix is achieved. It is'ne repeated melting necessary, which in turn makes the Abbrandverhältnisse be confusing.

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It is also known that a homogeneous alloy formation by powder metallurgy process is possible. However, since zirconia powder exhibits pyrophoric behavior, certain safety regulations are unavoidable with these technologies

The alloy NbZr 1 has a tolerance limit of + ^ 0.2% 'for the alloying element Zr, which must not be exceeded or fallen short because otherwise the mechanical properties are greatly impaired.

The aim of the invention is an economical process that allows the alloy formation between the two metals Nb and Zr in existing technical facilities.

Essence of the invention

The object of the invention is to provide a process for the production of said alloy in the electron beam multi-chamber furnace which simultaneously guarantees a high constancy of the Zr concentration in the Nb.

According to the invention, this is achieved by processing the required materials as follows:

1. Preparation of a melting rod of pure niobium with square cross section.

2o producing a Zirkpniujableches or -bandes and the bundling of both materials according to the predetermined concentration (see Figures 1 and 2).

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3. Melting of the bundled melting rod in the electron beam multi-chamber furnace to strand 0 60 mm under the following conditions:

- Beam current: '' '2.4 A Acceleration voltage: 24 kV

Radiation power: 57.6 k W

- Melting rate: II5 - 130 g / min.

-4 - Vacuum working vacuum: 1 χ 10 torr

- Beam sharply focused with a focal spot diameter of about 5 nmr

-.Strahlpendelung

in x-light = crystallizer diameter in y-direction = 2/3 of the crystallizer diameter

The arrangement of the materials in the ablation rod takes into account the specifics of melting in the electron beam, i. h, which forms in the unit time forming melting droplets of niobium before falling the liquid zirconium and thus forms the "condition that

a) 6in Zr burnup of max. I5% respected as well

b) a homogeneous distribution of Zr in the liquid melt is possible.

1st embodiment

In a multi-chambered PMC furnace, a prepared fusible rod (scrap or virgin metal) of pure niobium is melted to a 0 60 mm strand. By a Schmie.deVorgang (temperature: 65Ο ⁰ G), the strand is pulled out to a square bar with the edge length of y \ mm (area = 961 mm).

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The adherent oxide skin is removed by sand blasting and then a zirconium tape is tied to the underside of the Nb rod using Nb wire. The dimensions of the Zr band are 0.55 × 28 mm, so that, taking into account the different material densities, a Zr content of 1.20 % is added.

With an average burnup at Zr of 15 % in compliance with the described furnace conditions, the finished alloy has a Zr ~ content of 1.0 + 0.1 % by a single remelting .

In the production of sheet metal and strip material from NbZr 1 fall back on the fly, which must be returned to the production process.

These cleanly treated wastes are pressed into Abschmelzstäben and remelted in the electron beam furnace to strand 0 60 mm. This scrap melt is analyzed in detail, then the strand is forged into a rod with a square cross-section.

The remelting of the NbZr-I scrap causes the Zr content to drop to 0.72%,

After the forged bar is cleaned by sandblasting, a zirconia correction tape may be applied to melt the finish alloy thereafter.

As in Example 1, 15 % burn-off is expected for Zr, ie the correction band must have the dimension 0.4 × 10.5 mm, so that again the average final analysis with 1.0 + 0.1 % is achieved. "\

Claims (1)

223 7 42 • ' invention sanction A process for the production of molten ingots of the alloy NbZr 1 in the electron beam furnace as a starting material of strip production, characterized in that forged Abschmelzstäbe square cross section made of pure niobium or remelted recycled scraps, bundled with prepared zirconium sheets or strips corresponding to the predetermined concentration and Electron beam multi-chamber furnace to strands 0 60 mm, h. by one-off melting'under the following conditions:   - Beam current: "2.4 A - Acceleration voltage: 24 kV - Beam power:. 57.6 kW - Melting rate: 115 - 130 g / min. - Work vacuum in the recipient:. 1 x 10 torr - Beam sharply focused with a focal spot diameter of ca, 5 nm - beam oscillation in x-direction = crystallizer diameter in the y direction, = 2/3 of the crystallizer diameter ) are processed. For this purpose ή Page