SU891762A1 - Grease for hot metal extrusion - Google Patents

Description

(54) LUBRICANTS FOR HOT PRESSING OF GOTHS

I

The invention relates to the processing of metals by pressure, in particular to technological lubricants, for hot pressing of metals, and can be used in the production by the method of hot pressing of articles from powder materials.

During hot pressing of products from powder materials, lubricant is applied to the workpiece, the latter is heated, and then it is pressed.

Due to the fact that the surface of the blanks of powder materials is porous, the lubricants used must simultaneously with satisfactory antifriction properties also have good protective properties against oxidation.

It is known to use in the processing of metals the pressure of graphite-based lubricating compositions with various additives of aqueous oil suspensions.

Known lubricant containing, wt.%:

Graphite 25-35 Boer 11-13 Sulforous Cadmium 11-15 Talc. 5-6 Alkylaryl Sulfonate 1-2 Water. Also known grease 2, containing, wt.%:

ten

Graphite 30-35 P OLI acrylamide .8-10 Water Else

The disadvantage of graphite-containing mixtures

15 of them is their high carburizing ability, and in the case of hot pressing of blanks of powder materials, the surface of which is more porous than cast, there is a large

20 the likelihood of carburizing the surface, which will further lead to intergranular corrosion of products. 3 No-graphite greases for hot pressing are known. For example, lubricant 33 containing, in weight,%: Vermiculite 10-30 Sodium tripolyphosphate 5-15 Mineral oil Remaining The disadvantage of this lubricant is the presence in its composition of oil decomposable at high temperature with carbon evolution, which leads to carburization. Known lubricant 43, containing, in wt%: 20-26 Glass powder 15-17 Liquid glass 4-20 Up to 100 A disadvantage of known lubricant when used for hot pressing a billet of powder materials is its low antifriction properties. This is due to the fact that when the blanks are heated, the lubricant on their surface burns through, and due to the porosity of the surface of the blanks of powder materials, oxidation occurs at the grain boundaries. The latter, when hot pressed, leads to the appearance of annular tears and scratches. The reduced antifriction properties of burnt lubricant also contribute to this. Note. Compounds 2,3 and 4 - the proposed lubricant; 55 compositions 1 and 5 - a lubricant with a component content exceeding the specified limits; 4 The purpose of the invention is to increase the anti-friction properties of the lubricant. The goal is achieved by the fact that the lubricant containing liquid glass, borax and water additionally contains alumina in the following ratio of components, wt.%: Liquid glass 14-20 Drill 3-5 Aluminum oxide 20-32 Water Up to 100 Preparation of lubricant is carried out as follows in a way. Liquid glass is dissolved in about 1/3 of the calculated amount of water in a stainless steel tank, then the borax aqueous solution is added, mixed, and the aluminum oxide is poured while mixing is continued. The table shows the composition of lubricants. Testing of lubricants is carried out on blanks of 63x15x150 mm in size from dispersion-strengthened powder material with 1.5-2% dispersed TlOg oxide. The lubricant is applied to the workpiece by the method of dipping, dried at a C, then the workpiece with the applied lubricant is heated under pressing to. P50 ° C. With the use of the proposed lubricant, a tube of 18, 2.0 mm is pressed. Table 1 ; Composition 6 is a known lubricant, in order to preserve the consistency of the lubricant providing it with a satisfactory coating capacity, the total content of borax, water glass and alumina should be in the range of 40-50%. Therefore, the maximum content of alumina corresponds to the minimum content of borax and liquid glass and vice versa.

After pressing, the grease from the extruded tubes is removed in an alkaline melt containing and

NaCl at PO-430 ° C. Templates are cut off the tubes and microfibers are manufactured to study the oxidation of grain boundaries. The tubes are visually inspected using a periscope outer and inner surfaces.

Claims (4)

The results of the test lubricants are given in table 2. From Table 2 it follows that when using compositions 2.3 and 4, the pipes have a smooth surface, no defects are marked. In the same case, the lowest pressing forces and the absence of oxidation of the grain boundaries of the metal were observed, which indicates high antifriction and. protective properties of used lubricants. The use of compounds 1 and 5 leads to an increase in pressing forces and a deterioration in the quality of the surface and the internal structure of the pipes, since the lubricant in the first case involves that hot melt, and in the second - a low melt, which reduces its antifriction and protective properties. Known lubricant 6, as the most fusible in the process of heating flows from the blanks and burns through, as a result does not protect the metal from. oxidation of grain boundaries. This leads to a sharp deterioration in the surface quality of the pipes, an increase in the pressing force. Thus, the proposed lubricant compared with the known has a higher anti-friction properties. This is due to the fact that powdered alumina in a water solution of liquid glass and borax has good coating properties, and during heating, combines with the other components, it forms a vitreous coating that prevents the metal from oxidation and has high antifriction properties Press the process either. In addition, the proposed lubricant does not contain components that are scarce or labor-intensive in the preparation (e.g. glass powder), as well as substances harmful to the environment, which expands the practical possibility of its use. Formula of the invention A lubricant for hot pressing metals containing borax, glass and water, characterized in that, in order to increase the anti-friction properties of the lubricant, it additionally contains alumina in the following ratio of components, weight%:: Bura3-5 Liquid glass 14-20 Aluminum oxide 20-32 In Yes Do 100 Sources of information taken into account during the examination 1. USSR author's certificate Yu M 3/02, 1974. 414290, class C USSR certificate 2. Author's No. 300502, cl. C 10 M 3/30, 1971. 3. USSR author's certificate number 520391, cl. C 10 M 5/02, 1975. 4. USSR author's certificate number 696047, cl. C 10 M 3/02, 1979 (prototype).