Lubricant combination and process for preparation thereof

The invention relates to a learning for powder metallurgy and the lubricant composition and method for the preparation of the lubricant composition and use thereof. Specifically, the invention relates to a lubricant comprising at least two kinds of the lubricant composition.

Powdered metal such as powdered iron, is used for preparing small, accurate complex parts such as gears. The powdery metal process of manufacturing of such metal components, comprising the following steps:

The said powdered metal and lubricant and other additive a mixture obtained by mixing,

The obtained mixture is poured in to a mould, in order to form the part for pressing, usually adopts 200-1000MPa to high-pressure,

Ejector member in from the mold,

High-temperature treatment to the part in order to decompose and remove said lubricant, and to which said parts in all of the metal particles to sinter together,

And the component cooling, then, the use can be carried out.

Lubricant added to the metal powder with a plurality of reasons. One reason is that their through lubricating the compressing process in the inside of the said powder, used for the sintering is favorable to the production of a press. By the selection of a suitable lubricant, the regular needs can be obtained relatively high density. Moreover, the lubricant can provide the necessary lubrication, goes against states from the mould it is necessary in the compression part. Not fully lubricated in the ejection process will be because of excessive friction, and the abrasion and scuffing the surface of the mould, thereby leading to premature the die is not qualified. Not the problems brought about by the sufficient lubrication, can be used to resolve two methods: a method is to improve the consumption of the lubricant, another method is to choose more effective lubricant. However, the method of improving the lubricant consumption, will encounter the undesirable side effects, because through better "internal lubricating" the obtained density increases, the increase of the volume of the lubricant will be weaken. Therefore, better choice should be more effective is the lubricant choice. However, it has been found that this kind of method, there is a difficult problem, because an effective lubricant to the mixture of a powder characteristic trend in the generation of a negative role.

Other possibility is to find new ways, in order to combine or use of the lubricant, so as to make them more effective. The present invention relates to this kind of the combination of the lubricant. The thinking of this invention of course is not limited to the current and a known lubricant, and it is also suitable for other lubricant in the future.

In accordance with the present invention, the preparation of the novel lubricant effectively states method comprises the following steps:

Select 1st 2nd lubricant powder and the lubricant powder, wherein said 1st lubricant is selected from fatty acid bisamide and fatty acid mono-amide, and the 2nd lubricant is selected from metal soap;

Mixing the lubricant powder; and

The mixture is subjected to can be bonded to the lubricant particle 2nd 1st lubricant particle to form a lubricant 1st on nuclear agglomerated particles of the treatment of the condition of the lubricant composition, the surface of the core by the 2nd coated by a lubricant particle.

The 1st to the main purpose of the lubricant is lubricating property of the powder, it will give a relatively high-density and low ejection force, and the 2nd the main purpose of the lubricant is to provide a powder having a good performance of the metal powder mixture, such as high flow rate and uniform filling of the mould, it is equally provide the high productivity and the pressing part has a uniform density distribution.

1st embodiment is of the lubricant such as fatty acid bisamides ethylidene -double-palmitic acid amide (palmitinamide), ethylene-bis-stearamide, ethylene-bis-peanut acid amide (arachinamide), ethylidene-double- shan 萮suan amide, Hexylidene-double-palmitic acid amide, Hexylidene-bis-stearamide, Hexylidene-bis-peanut acid amide, Hexylidene-double- shan 萮suan amide, ethylene-bis -12-hydroxy-stearamide, b stearyl acyl adipic diamide and fatty acid mono-amide such as palmitic acid amide, stearic amide, peanut acid amide, shan 萮suan amide, oleic acid amide. Furthermore, the 1st lubricant can include by two or more lubricant a solid mixture.

The 2nd lubricant can be selected from metal soap like zinc stearate, lithium stearate.

Preferably, the lubricant particles are nearly spherical as possible, because the ball will lead to the greatest and the flow rate of the apparent density.

More preferably, the 1st lubricant has an average particle size greater than the particle size of the lubricant 2nd. Particularly preferably, the average particle size of the lubricant 1st 2nd lubricant particle size is 2-3 times, most preferably, the 1st lubricant is at least an average particle size of the 15  m, said 2nd lubricant to an average particle size of at most the 6  m. Furthermore, the lubricant also found the number of 1st should be preferably of the weight of the composition of the total lubricant 60-90% between.

Provided the conditions of bonding lubricant particle 1st method comprises at a certain temperature and sufficient lubricant and 1st 2nd the particles of the lubricant is formed between the physical adhesion to the time interval of the lubricant and/or 1st 2nd heating particles of lubricant.

With a metal powder when mixing, optionally the lubricant composition with the concentration of the conventional solid lubricant, its suitable range is 0.1-5% by weight, preferably 0.3-1%.

Metal powder of interest is preferably iron-based powder. Examples of iron-based powder is alloyed iron-based powder, such as iron powder or is with diffusion bonded to the iron particles of the iron powder of the alloy elements. The iron-based powder can also be substantially pure iron powder and the alloy element (for example, it, such as being selected from Ni, cu, Cr, Mo, Mn, P, Si, V and W) of the mixture. Different elements of the alloy of the various different the content are as follows: for Ni 0-10 weight %, preferably 1-6 weight % ; for cu 0-8 weight %, preferably 1-5 weight % ; Cr to 0-25 weight %, preferably 0-12 weight % ; Mo to 0-5 weight %, preferably 0-3 weight % ; for P 0-1 weight %, preferably 0-0.6 weight % ; Si to 0-5 weight %, preferably 0-2 weight % ; for V 0-3 weight %, preferably 0-1 weight % ; W to 0-10 weight %, preferably 0-4 weight %.

The iron-based powder is atomized powder or sponge iron powder.

The particle size of the iron-based powder according to the end use of the sintered product is selected.

Therefore, lubricant composition of the present invention is provided with a 1st nuclear the surface modification of the lubricant of the lubricant, wherein the core surface is coated by a 2nd particles of lubricant. The lubricant composition with the same lubricant compared with mechanical mixture, the performance of the lubricant composition is more excellent. The same lubricant melting and then solidify the mixture of this is also the case.