SU1576299A1 - Composition for impregnating abrasive tool - Google Patents

Abstract

The invention relates to the abrasive treatment of high-temperature alloys without the use of coolant or with the use of oil coolant. The aim of the invention is to increase the durability of the abrasive tool when grinding superalloys in self-sharpening mode. The composition contains water, borax, alkali metal fluoride, chromium oxide and ammonium hydrogen phosphate, for example, ammophos, in the following ratio, wt.%: Borax 10-20

alkali metal fluoride 1-3

chromium oxide 4-10

hydrophosphate ammonium (mono or diammonium phosphate or their mixture) 2-5

water the rest. 4 tab.

Description

The invention relates to the abrasive treatment of heat-resistant alloys, namely, compositions for impregnating an abrasive tool on a ceramic bond, operating in self-sharpening mode without coolant or using oil coolant.

The purpose of the invention is to increase the stability of the abrasive tool when grinding superalloys in self-sharpening mode.

The proposed composition for impregnating an abrasive tool contains water, borax, alkali metal fluoride, chromium oxide and ammonium hydrogen phosphate in the following ratio of components, May. %

10-20

Borax

fluoride

alkaline

metal

Oxide

chrome

1-3

4-10

Ammonium hydrogen phosphate 2-5 Water Else Potassium, sodium or lithium fluoride may be used as an alkali metal fluoride.

As ammonium hydrogen phosphate, it is mono- or diammonium phosphate or their mixture (90% mono- and 103 diammonium phosphate). Decreasing the content of components below the described values does not ensure the formation of a sufficient amount of shielding film (due to the lack of ammonium phosphates and chromium oxide), does not occur sufficiently to self-sharpen the softening of the ceramic bond (due to the lack of alkali metal fluoride), and also does not provide sufficient impregnator access to the grinding zone and to the newly opened grains (due to the lack of low-melting borax). By increasing

H t

content of components in excess of 15762994

form chemical shielding

there is no further increase in wheel durability, and an excessive amount of fluoride leads to increased wheel wear “

The impregnating composition is prepared by dissolving in a hot water (70 - 90 ° C) the required amount of borax, alkali metal fluoride and ammonium phosphate. Chromium oxide is introduced into the prepared supersaturated solution with constant stirring.

The circles for impregnation are cleaned of dirt and dust and calcined at a temperature of about 150 ° C. The hot circles are placed in a hot impregnating compound at 1/2 - behind the height. Impregnation is carried out by the method of free capillary raising with constant stirring of the impregnating composition. The circles are kept in the impregnating composition for 3 to 10 minutes. After impregnation, the circles are dried in air for 30–60 minutes, and then in an oven at a temperature of OS –95 ° C for 5–6 hours. After drying, the circles are ready for operation.

In the dried abrasive tool, there is an impregnator film on the surface of the grains and ligament consisting of low-melting (drill) and refractory (alkali metal fluoride and chromium oxide) phases, as well as phases with an average melting point (ammonium phosphate). When grinding under the action of high temperatures, the drill melts (melting point 75 ° C) and provides transportation of more refractory phases to the treatment zone and to the opening as a result of self-shaking grain. Once in the grinding zone, the drill is dehydrated (at 300 - 00 ° C) and crystallizes, in this state it acts as a solid lubricant (the melting point of anhydrous sodium tetraborate). The diammonium phosphate in the grinding zone decomposes at 70 ° C, releases ammonia, and is converted to monoammonium phosphate. At higher temperatures, the monoammonium phosphate is further decomposed with the release of water to ammonium pyrophosphate, and then to

five

20

25

thirty

35

40

45

50

phosphate and nitride films. Phosphates have a very low coefficient of friction (0.05) t but are not heat resistant, nitrides are heat resistant, but have a high coefficient of friction. The chromium oxide particles, having a sufficiently high hardness, are embedded in the adhered metal and prevent it from setting at both low and high temperatures. The combination of shielding films formed by chemical put on the place and mechanical paths, eliminates intensive setting. Phosphate and borate films with a low coefficient of friction prevent metal from sticking to slipping and heavy grains and ligaments.

In the process of impregnating the circles, the ceramic bond softens. In the impregnating solution there are fluoride ions (the product of fluoride dissociation) and hydrogen (the product of the dissociation of mono- and diammonium phosphate). These ions react with silicon oxide, which forms the basis of the ceramic bond. The reaction produces gaseous silicon fluoride and water. The softening of the ceramic bond promotes better self-honing of the abrasive tool.

Thus, the use of the proposed impregnating composition ensures the stable operation of the abrasive tool in the self-tapering mode, eliminates the intensive fusion of the metal to the grain. This makes it possible to drastically reduce the number of edits and increase tool life.

Potassium fluoride, sodium and lithium dissolve when dissolved in water to form fluoride ion. Therefore, they are equivalent.

When dissolved in water, mono- and diammonium phosphate dissociates to form hydrogen ions, and when decomposed in the grinding zone, ammonium metaphosphate is formed. At the same time, similar results are ensured, which makes it possible to recognize them as equivalents

When alkali metal or lithium fluoride is used as the alkali metal fluoride, the abrasive tool is non-hygroscopic and

ammonium glass-forming phosphate - can be operated

melt melt at 280 ° C. Ammonium metaphosphate acts as a lubricant, and its decomposition products react with metal adhered to grains,

subject to

high humidity. I

Example 1. Polished samples from heat resistant alloy 787

five

0

five

0

five

0

five

50

phosphate and nitride films. Phosphates have a very low coefficient of friction (0.05) t but are not heat resistant, nitrides are heat resistant, but have a high coefficient of friction. The chromium oxide particles, having a sufficiently high hardness, are embedded in the adhered metal and prevent it from setting at both low and high temperatures. The combination of screening films that are chemically formed by the place and mechanical paths, eliminates the intensive setting. Phosphate and borate films with a low coefficient of friction prevent metal from sticking to sliding and pressing grains and ligaments.

In the process of impregnating the circles, the ceramic bond softens. In the impregnating solution there are fluoride ions (the product of fluoride dissociation) and hydrogen (the product of the dissociation of mono- and diammonium phosphate). These ions react with silicon oxide, which forms the basis of the ceramic binder. The reaction produces gaseous silicon fluoride and water. The softening of the ceramic bond promotes better self-honing abrasive tools,

Thus, the use of the proposed impregnating composition ensures the stable operation of the abrasive tool in the self-treating mode, eliminates the intensive fusion of the metal for the grain. This makes it possible to drastically reduce the number of edits and increase tool life.

Potassium fluoride, sodium and lithium dissolve when dissolved in water to form fluoride ion. Therefore, they are equivalent.

When dissolved in water, mono- and diammonium phosphate dissociates to form hydrogen ions, and upon decomposition in the grinding zone they form ammonium metaphosphate. In so doing, similar results are provided, which makes it possible to recognize them as equivalents.

When alkali metal or lithium fluoride is used as alkali metal fluoride, impregnated abraemol can be used

subject to

high humidity. I

Example 1. Polished samples from heat resistant alloy 787

51

circles, impregnated with known and described impregnating compositions. Grinding wheels characteristics 25A. | 0-P.S2.6, K5.A soaked with soy tavami, are given in Table. one.

The tests were carried out without the use of coolant in the following mode: a circle speed of 35 m / s, a table speed of 0.2 m / cj grinding depth of 0.05 mm / / dv.khd. To eliminate the effect of hardness of the circles, they were tested twice: before and after impregnation. The ratios of grinding impregnated wheel parameters to non-impregnated grinding wheel parameters were determined. The following parameters were chosen as process parameters: cutting capacity (mm / s), specific grinding work (J / mm), coefficient of cutting ability (mm / N-s), grinding coefficient (mm metal / mm abrasive) and durability of the circle (s) . In tab. 2 summarized the relative parameters.

As can be seen from the table. 2, the use of the described impregnating composition provides in comparison with the known increase in wheel durability by 1.7 2.3 times and a coefficient of cutting ability by 1.5 - 2.0 times, as well as a decrease in wear of wheels by 1.15 - 1.3 times and specific grinding work 1.2 - 1.6 times. The best results showed composition

Example 2. Polished parts of superalloys EI787 and

ten

762996

edit frequency and processing manufacturer. The results are summarized in table. four.

As can be seen from the table. t, the use of the proposed impregnating composition in comparison with the known increases the processing performance by 1.1 - 1.25 times, the stability of the circles by 1.8 - 2.25 times and reduces the consumption of circles by 1.3 - 1.55 times.

When using equivalents (potassium, sodium or lithium fluoride, as well as mono- or diammonium phosphate 15 or ammophos), approximately the same grinding parameters are provided: differences in wheel consumption do not exceed 18–22%, and in processing productivity — 1 f –16%

Claims (1)

With the exclusion of chromium oxide from the composition described, the performance properties of the impregnated wheels are sharply reduced. Invention Formula A ceramic bonded abrasive tool composition containing borax, alkali metal fluoride, ammonium salt and water, characterized in that. The composition additionally contains chromium oxide to increase tool life when grinding superalloys in self-sharpening mode, and ammonium hydrogen phosphate as the ammonium salt at the following 35 ratio of ingredients, wt.%: 20 25 thirty ZhS 6-U alloy Not impregnated i table 2 Table D