JPH0699728B2 - Method for manufacturing rolled metal chrome - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rolled metal chromium body having a relative density of 95% or more and a purity of 99.9% or more, and a method for producing the same. Metallic chromium is one of the extremely useful metals because it has excellent chemical resistance such as acid resistance and alkali resistance even at high temperatures and excellent weather resistance. However, in spite of having such excellent properties, since the toughness is low at low temperature and the processing is difficult, the pure chromium and the chromium-based alloys have not been practically used.

The present invention provides a rolled metal chromium body and a method for producing the same, which utilizes the original characteristics of the metal chromium.

[Prior Art and its Problems] As a forming method of metallic chromium, a method of forming a metallic chromium powder into a plate shape through steps of powder rolling (cold), sintering, re-rolling and annealing has been known so far. (Japanese Patent Laid-Open No. 58-55
No. 502).

However, this method (1) requires many steps and is complicated in operation. (2) In cold rolling, only the gaps between particles are filled, and the deformation of the powder particles themselves is difficult to proceed.
(3) There are problems such as low relative density of the obtained plate.

[Means for Solving Problems] The present invention provides a rolled metal chromium body having a relative density of 95% or more and a purity of 99.9% or more, and as a method for producing the same, a purity of 99.9% or more. The present invention provides a method for producing a metal chrome rolled body having a relative density of 95% or more, which is characterized by enclosing metal chrome powder in a hermetically sealed container, subjecting it to vacuum treatment, and heating and rolling this at 600 to 1000 ° C. .

The purity of metallic chromium, which is the starting material in the present invention, is 99.9.
% Or more, and the inclusion of impurities such as carbon and nitrogen should be avoided as much as possible. This is because the toughness of the rolled body can be increased by removing these impurities. Such high-purity metal chromium powder is obtained by electrolyzing a chromium salt solution, or by purifying a chromium salt solution by a solvent extraction method, and oxidizing the obtained chromium salt solution or the chromium salt obtained from this solution. It can be obtained by pulverizing metal chromic acid obtained by reducing the obtained chromic acid by a hydrogen reduction method or the like. The particle size of the metallic chromium powder in the present invention may be small, but is usually 100 μm.
Below, those having a thickness of 10 to 80 μm are preferably adopted.

The container for enclosing the metal chrome powder is not particularly limited in terms of material and shape as long as it is a container having vacuum resistance and heat resistance, but a stainless steel container is used in consideration of economical efficiency. See. Further, the shape of the container is appropriately determined according to the desired shape of the rolled body.

In the present invention, vacuum evacuation is performed after the metal chromium powder is sealed in the sealed container. This evacuation is performed for the purpose of flushing the adsorbed gas that causes brittleness of metallic chromium. In order to more strictly remove the harmful adsorption gas, first replace the inside of the sealed container with an inert gas such as argon or helium, and then evacuate to a vacuum degree of about 10 ^-5 mmHg using a rotary pump or a diffusion pump, 350-700
Evacuate while heating to a temperature of ℃, finally vacuum degree 10 ^-5
It is preferable to set it to mmHg or more.

Next, after performing the above vacuum treatment, heat rolling is performed. The heating temperature is 600 to 1000 ° C, preferably 650 to 900 ° C.
In this temperature range, the solid solubility of nitrogen in metallic chromium is 3 to
This is because it is as low as 17 ppm and recrystallization can be suppressed. Further, the rolling ratio is preferably 70% or more, and particularly preferably 80% or more. This is because by increasing the rolling rate, the relative density becomes relatively high and a stronger rolled body can be obtained.

Here, the rolling rate is obtained by the cross-sectional area reduction rate shown in the following equation.

d: Rolling ratio to: Sample cross-sectional area before rolling t: Sample cross-sectional area after rolling After the above steps, cooling is performed to obtain a high-density metal chromium rolled body of the present invention.

EFFECTS OF THE INVENTION According to the present invention, a rolled metal chromium body having a relative density of 95% or more can be obtained by a relatively simple operation.

Further, the obtained rolled body is rich in malleability and ductility as compared with the conventionally known sintered body, and the secondary processing is facilitated, and it can be further processed into an article having an arbitrary shape. Such a rolled body has not been heretofore known. Therefore, the rolled metal chromium body obtained according to the present invention can be used as it is or subjected to secondary processing, and can sufficiently withstand use even under severe conditions such as high temperature and strong acid or strong alkali.

[Examples] Examples of producing a rolled metal chromium body of the present invention will be described below with reference to Examples. The invention is in no way limited by these examples. All% in the examples mean% by weight.

Example 1 Fe: 0.019%, C: 0.003 as impurities in an elliptical stainless steel container having a length of 125 mm, a cross-sectional area of 33 mm and a minor axis of 22 mm.
%, O: 0.045%, S: 0.001%, N: 0.004%, H: 0.0002%,
P: 0.0009%, Al: 00007%, Si: 0.013%, Pb: 0.0001%, C
u: 0.0001% metal chromium powder (average particle diameter: major axis 66μ
m, short diameter 33 μm), and then argon was sealed by a stainless pipe having an inner diameter of 2 mm provided at one end of the hermetically sealed container and held for about 15 minutes. Then, in this container at room temperature for 10
-Use a rotary pump to evacuate to a vacuum level of ^-5 mmHg or higher, and then load the container into a horizontal electric furnace, and heat it at 350 ℃, 450
It was heated stepwise at each temperature of ℃ and 680 ℃, evacuated at each temperature for a certain period of time, and evacuated until the degree of vacuum reached 10 ^-5 mmHg.

Then, the roll diameter 200 mmφ, charging the sealed container to a heating and rolling device having a roll rotation speed of 17 rpm, and heating to 750 ° C.,
After rolling to a rolling ratio of 80% and cooling, the metal chrome plate was taken out. The relative density of the chromium metal plate was 97% as measured by the Archimedes method. The obtained metal claw plate was embedded in epoxy resin, and the hardness was measured with a Vickers hardness meter (M type made by Shimadzu) under a load of 100 g. 250 / HV
Met.

Examples 2 to 8 Using the same metallic chromium powder as that used in Example 1 as the starting material, heat rolling was performed under the conditions shown in the following table in the same manner as in Example 1. The results are shown in the table.

Claims (2)

[Claims] 1. In a method for producing a rolled metal chromium body having a purity of 99.9% or more and a relative density of 95% or more, the metal chromium powder having a purity of 99.9% or more is sealed in a hermetically sealed container and vacuumed. A method for producing a rolled metal chrome body, which comprises subjecting the material to heat treatment and heating and rolling at 600 to 1000 ° C. 2. The method for producing a rolled metal chromium body according to claim 1, wherein the rolling ratio is 70% or more.