KR950014356B1 - Method of manufacturing composite materials of iron-siliconcarbide - Google Patents

Abstract

The iron-silicon carbide based composite material is manufactured by (a) mixing methanol with the mixed powders of less than 30 vol% silicon carbide and more than 70 vol% iron powder, (b) drying the mixture in nonoxidative state, (c) pressing the dried body under more than 50kg/mm2 of pressure and at room temperature to make a green compact, (d) sintering the green compact at 900-950 deg.C for 1-1.5 hrs.

Description

Manufacturing method of iron-silicon carbide (Fe-SiC) composite material

1 is a close-up of the tissue showing the binding state of the iron-silicon carbide interface

2 is an enlarged photograph of the structure of the iron-silicon carbide composite.

The present invention relates to a method for producing an iron-silicon carbide (Fe-SiC) composite material. The most disadvantage is that iron materials, which are most widely used in the industry, are heavier than competing metals such as aluminum. Thus, many people pursued to strengthen the properties of iron and at the same time make such materials lighter.

However, there have been many studies on the method of alloying iron and alloying elements by chemical reaction in the molten state of iron by adding alloying elements to the conventional ferrous metals. Manufacturing techniques have not been introduced yet.

It is an object of the present invention to provide a method for producing a light yet strong iron composite by adding silicon carbide to ferrous metals.

The present invention by achieving the above object is a volume% to the iron powder, adding a silicon carbide powder of 30% or less and then mixing it with methanol; Drying the mixture under a condition that is not oxidized, and then pressing at a pressure of 50 kg / mm 2 or more at room temperature to form a green compact; And it relates to a method for producing an iron-silicon carbide composite material comprising the step of sintering the molded green compact at 900-950 ℃ 1-1.5 hours.

The present invention will be described based on the following examples.

Example 1

Powders of iron and silicon carbide as shown in Table 1 were selected. These powders are particulate powders that are commercially available as products, and the particle size is not limited to the degree of variation.

TABLE 1

The ferrous powder and silicon carbide powder were mixed in a volume ratio of 80.20 in methanol (methyl alcohol), sufficiently blended in a low speed mixer (Mixer), and then dried in an anoxic furnace at 200 ° C. without oxidation. . At this time, the drying temperature and time was not limited separately.

In addition, the reason for adding methanol to the powder raw material is to prevent dust generation when mixing because the silicon carbide powder is harmful. Thus, for this purpose, not only methanol but also a volatile solution may be added.

In order to minimize the possible porosity of the dried mixed powder, green compact was formed by applying a pressure of 50kg / mm2 or more at room temperature and then sintered in an argon atmosphere for 1 hour-2 hours in the range of 800-1000 ° C. It was. The most important thing in the combination of iron and silicon carbide is to see if an interfacial reaction occurs between the two materials. If no interfacial reaction occurs between the two materials, the interfacial bonding strength is weak and easily breaks.

After sintering the green bulk pact prepared in the above process, the interface reaction was measured.

Table 2 shows the measurement results.

TABLE 2

As can be seen from Table 2, when the sintering temperature is 850 ℃ or less, when the sintering time was 1 hour or 2 hours, the reaction was insufficient, and the surface active state was poor, and the sintering time was sintering at 950 ℃ for 2 hours or more. Or, when the sintering temperature is at least 1000 ° C., SiC is excessively dissolved, and the interface bonding state is also poor.

Therefore, it was most preferable to set the sintering temperature to 900-950 degreeC and the sintering time to 1-1.5 hours.

Meanwhile, as a result of sintering the green coarse pact at 950 ° C. for 1 hour using a scanning electron microscope, it can be seen that a reactant is formed between the iron particles and the silicon carbide particles, thereby strongly binding the two materials to each other. 1 is an enlarged photograph of the tissue of the green compact. The X phase between the A phase (Fe) and the B phase (SiC) in FIG. 1 is a reaction phase, which was found to be Fe ³ Si in X-ray rotation analysis. This is produced by reacting with Fe as Si atoms in SiC diffuse into the Fe matrix, which can be represented by the following scheme.

3Fe + SiC = Fe ³ Si + C (graphite)

Example 2

A green compact was prepared by subjecting Fe to 10%, 20%, and 30% of SiC in a volume ratio, respectively, by the process of Example 1, and sintering the green compact at 900-950 ° C. for 1-1.5 hours. After that, its physical properties were measured. At this time, if the silicon carbide is added too much, the material may be fragile, so the SiC addition range was limited to 30% by volume.

Table 3 shows the results of measuring the physical properties.

TABLE 3

As shown in Table 3, the density of the comparative material without addition of silicon carbide was 5.97 g / cm 3, and when the 10% silicon carbide was added by volume ratio, the density was 5.37 g / cm 3, resulting in an 11% weight loss effect. Brought. In addition, the addition of 20% and 30% silicon carbide showed a weight loss of 16% and 30%, respectively.

In the hardness (Hv), on the other hand, in the case of iron without silicon carbide, the hardness is 60, whereas silicon carbide is added 10%, 20% and 30%, respectively, 96 (60% increase) and 119, respectively. (About 100% increase) and 132 (120% increase), it was found that the hardness was always significant.

2 is an enlarged photograph of the tissue of the present invention, showing that the silicon carbide particles are uniformly distributed in the tissue.

The present invention is a composite of silicon carbide, a ceramic material in ferrous metal, to provide a high-strength iron material without the addition of expensive alloying elements, it is expected that the ripple effect on the steel industry will be very large in the future do.

Claims (1)

After adding a volume of silicon carbide powder of 30% or less to iron powder, and mixing it with methanol, drying the mixture under non-oxidizing conditions, and then pressing it at a pressure of 50 kg / mm2 or above at room temperature to increase the size of the green carbide. Shaping; And sintering the molded green compact at 900-950 ° C. for 1-1.5 hours.