JPS5822304A - Molding auxiliary for raw powder for powder metallurgy - Google Patents

Abstract

PURPOSE:To obtain a molding auxiliary that is highly soluble in organic solvents, is excellent in the granulating ability and the molding ability, and can easily be removed in a preliminaly sintering step, by adding an olefin oxide and/or a fatty acid to a polyalcohol ester condensate. CONSTITUTION:A compound that has been prepared by adding an olefin oxide and/or a fatty acid to a polyalcohol ester condensate is used as a molding auxiliary for a raw powder for powder metallurgy. As a polyalcohol ester used here is preferred glycerin, and also other glycols and sorbitols are effective. As a olefin oxide, ethylene oxide is preferable, other oxides such as propylene are used. As a fatty acids, higher fatty acids containing 8 or more carbon atoms such as caprylic acid are preferred. Using the above molding auxiliary, a better compact powder can be obtained, and the occurrence of cavity and pores of the sintered body is less.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a III, shaping or lubricant necessary when press-molding powder by a powder metallurgy method,
Suitable for press-molding mixed powders of nonmetallic powders such as nitrides, oxides, borides, sulfides, and silicides, and metal powders, or mixed powders with metal powders. 9. Forming of raw material powder for powder metallurgy. Regarding auxiliaries.

In general, manufacturing processes in powder metallurgy can be roughly divided into a powder mixing and pulverizing process, a granulation process, a drying and sieving process, a press molding process, a preliminary sintering process, and a sintering process.

In the internal granulation process of these O processes, the powder is made easy to handle, and the shape, size, and hardness of the granulated powder are adjusted based on the fluidity and filling properties of the powder in the subsequent press forming process. Therefore, it is necessary to mix a molding agent or a lubricant in the granulated powder. In press forming worker 1,
A friend that alleviates the friction between the powders sprinkled into the metal, the friction between the powder sprinkled in the gold layer and the mold wall, and the friction at the contact area between the metal bottle and the goo. A molding agent or lubricant is required to prevent the shape of the pressed powder compact from collapsing.As molding agents or molding aids such as #i lubricant, conventionally used Examples of the oxygen used include paraffin, camphor, stearic acid, and zinc stearate.

Among these conventional molding aids, puffin has
Due to various problems such as cost and solubility in the work, there is no suitable S medium.Generally, acetone is used as a solvent, but since the solubility is low, it is possible to mix it with powder by raising the temperature slightly to form a paraffin til. It is taken. At this point, the distribution of 227470 in the powder becomes non-uniform, causing problems such as clogging of the mesh during the drying and sieving process, and a part of the powder containing many puffins not passing through the mesh.

In addition, forming aids are unnecessary and harmful in the sintering process, so they are removed in the preliminary sintering process, but paraffin decomposes in the preliminary sintering process and turns into carbon, which is then inserted into the compact*. The pre-sintering method and conditions are very difficult due to problems such as adhesion, and in particular, when pre-sintering in a vacuum, decomposed paraffin adheres to the inside of the furnace, reducing the degree of vacuum.

Furthermore, when a sintered body is obtained from a mixed powder using paraffin as a forming aid, cavities appear, which are thought to be caused by the non-uniform distribution of paraffin, and this poses the important problem of reducing the strength of the sintered body. be.

Camphor, which is used as a forming aid, is easily dissolved in ether, but poses problems in terms of operational safety and health.Although it dissolves in ethanol to an admirable degree, it poses problems in the granulation process due to the evaporation rate of ethanol. Also compared to paraffin, camphor! i;! Due to the low AFi viscosity, the strength of the green compact is low, and if the stiffness of the green compact is low, cracks are likely to occur in the green compact after preliminary sintering, and cavities occur when the compact is sintered. The problem is that it is more likely to occur.

Stearic acid and lithium stearate! IFi uses methanol or ethanol as a solvent because there is no suitable solvent, but like camphor, there is brrt in the granulation process, and its low solubility makes it difficult to distribute uniformly in the powder during the granulation process, so The problem is that when it matures, it forms a nest and becomes a bird.

The present invention is a forming aid for powders suitable for powder metallurgy, which was completed as a result of repeated research aimed at solving the above-mentioned problems.

The forming aid for raw material powder of the present invention is a compound obtained by adding an olefin oxide and/or a fatty acid to a polyhydric alcohol ester condensate.

The molding aid for raw material powder of the present invention is easily soluble in organic solvents, particularly methanol, ethanol, acetone, etc., poses no problems in terms of handling and safety and hygiene, and is capable of forming olefin oxides and/or fatty acids. Because it is an added compound, it has adhesive and viscous properties, and these solubility, adhesive and viscous properties uniformly distribute the forming aid in the powder during the granulation process, resulting in the shape of the granulated powder. It eliminates variations in size and hardness and helps create stable granulated powder. In addition, in the press molding process, the molding aid for raw material powder of the present invention is obtained in order to reduce variations in the shape, size and hardness of the granulated powder, and to maintain appropriate stiffness and viscosity. When press molding using granulated powder, the molding aid is uniformly distributed in the granulated powder. Because the granulated powder has excellent fluidity and brightness, the green compact is evenly pressed. The powder compact has a high strength k, and the green compact has appropriate mold releasability, so that a molded product that is resistant to pressing and chipping can be obtained. In the preliminary sintering process, the forming aid for the raw material powder of the present invention evaporates at a low temperature and has an appropriate evaporation rate, so even during the gas decomposition of the forming aid, no gas is released into the green compact. has no adverse effect, and therefore no cracks occur in the green compact in the preliminary sintering process.

Green compact from which the molding aid of the present invention has been removed by preliminary sintering - When sintered, the molding aid is generally exposed directly and interveningly to the sintered body paste. An excellent sintered body without pores can be obtained.

The polyhydric alcohol esters used here include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and hexylene glycol.
sp, polyethylene/li:2-#, polyoxypropylene glycol, polyoxyalkylene glycol,
Polyoxyethylene propylene glycol, sorbitol, sorbitan, polyoxyethylene sorbitol, etc. are also effective, but judging from the manufacturing process of the molding aid O, glycerin is suitable for subsequent workability, stability, and safety. Olefin oxides include propylene oxide, l-butene oxide, inbutylene oxide, l-pentene oxide,
Although there are 2-pentene oxide, imbutylene oxide, etc., the forming aid for the raw material powder of the present invention obtained by adding edelene oxide is particularly suitable, judging from the granulation characteristics, press moldability, etc.

Fatty acids include animal and vegetable oil fatty acids, hydrogenated vegetable oil fatty acids, petroleum acids, etc. Among them, ^-class fatty acids with a prime number of 8 or more are suitable, such as caprylic acid, capric acid, myristic acid, valmitic acid, and stearin. Acid, aranic acid, behenic acid, cerotic acid, melisic acid, superic acid, azelaic acid, sepacunic acid, brassylic acid, elaidic acid, oleic acid, erucic acid, pen2urgonic acid,! There are Lugarin etc.

The molding aid for raw material powder of the present invention has high solubility in organic solvents, and has lubricity, viscosity, and #* properties, so it is extremely excellent in the granulation process and press molding process.
When the molding aid becomes unnecessary and is removed in the preliminary sintering process, the molding aid for the raw material powder of the present invention evaporates at a low temperature, and the evaporation rate is not rapid, but it evaporates in a small volume. It is an excellent shaping aid that leaves almost no residue even in a vacuum furnace.

Powder metallurgy includes porous parts, sintered steel, iron/copper alloys,
Nonferrous alloys, flat melting point alloys, heat-resistant and corrosion-resistant alloys, electrical contact materials,
The forming aid for raw material powder of the present invention is effective for nuclear materials, fiber lubricating materials, and M'7g materials, and is particularly effective for powder metallurgy-related materials that are easily affected by Iwt in cemented carbide and cermet pre-sintering processes. It has a remarkable effect. Also, 4m, 5m and 6a
As a molding aid for powders and metal powders containing group metal carbides, nitrides, metal powders, silicides, and sulfides, and metal powders or metal oxides, the molding aid for powders of the 0IIL group of the present invention is used. It is valid.

Next, the forming aid for raw material powder for @O secondary metallurgy of the present invention will be explained in detail according to Examples.

Example 1 Weight composition f 40% Ti (:!-1551W (7-15
1TiN-20 Example 2 Mixed and pulverized powder with a weight composition of 91'WC-5tiCO was mixed with a molding aid t3weight St, and granulated by the Tin Laid 2-ing method. 0.7, α9
A ton of shoulder-pressed powder was prepared, and this was made into a sintered body in the same manner as in Example 1. The molding aids used here were the following molding aids for raw material powder of the present invention a%b%C and paraffin d was added as a comparative molding aid.

A molding aid of the present invention in which ethylene oxide and calylic acid are added to a C1 glycerin condensate.

), the molding aid of the present invention in which propylene oxide and palmitic acid are added to a glycerin condensate.

The molding aid of the present invention is obtained by adding ethylene oxide and margaric acid to a C1 glycerin condensate.

Table 2 shows the conditions of the cavities and pores in each sintered body obtained by sintering specific pressure powders using the forming aids a, b, c, and d at different press pressures.

Table 2 * Mu: o, almost no burrows per sm B: 7-8 pieces C: There are more than 10 pieces. D: There are 20 or more pieces. From the results in Table 2, forming aid a for raw material powder of the present invention.

It was confirmed that the samples using b and c produced sufficiently dense sintered bodies even at a low press pressure of 0.5 toVd, and were superior to the comparative paraffin d.

In addition, the green compact using the molding aid aS b, of the present invention is as follows:
Example 3 Ethylene oxide and oleic alt were added to the glycerin condensate to each sample of the component layer shown in Example 3, and the present invention was obtained. 115% C%d1 with added molding aid for powder
・O1 with added Panhun, which is a molding aid for softness.
's Is h% 1, jt - Each sample is press-formed into a cylindrical shape at a rate of It/m.
After pre-sintering at 0°C for 1 hour, the total carbon content of each sample was analyzed, and the increase in amount of daughter carbon in the mixed pulverized powder before addition of the forming aid was determined.114
Indicated.

As a result of Table 4, the JI powder forming aid of the present invention has an increase in carbon content of 0.02 to 0.05 wt.
The increase in carbon content of the comparative molding aid using <27(n) is as large as α15 to 0.25% by weight, and the carbon content tends to vary widely.From this, it can be seen that the molding aid for raw material powder of the present invention It was confirmed that there was little residual carbon and that it was stable in terms of quality control.

Claims (1)

[Scope of Claims] +1) A molding aid for raw material powder for powder metallurgy, characterized by comprising a compound obtained by adding an olefin oxide and/or a fatty acid to a condensate of poly-1i alcohol esters. (2) A forming aid for powder metallurgy raw material powder according to claim 1, wherein the polyhydric alcohol ester comprises glycerin. (3) The olefin oxide consists of ethylene oxide and/or propylene oxide.
71 Forming aid for powder. (4) The above-mentioned fatty acid consists of a higher fatty acid having 8 or more carbon atoms.Claims 1 and 2.
1 [or a forming aid for powder metallurgy raw material powder according to item 3.