SU740863A1 - Carburiser for gas and low-temperature nitrocarburisation of steel articles - Google Patents

Description

(54) CARBUY13ATOR FOR GAS LOW TEA OF CURRENT NITROCEMENT OF STEEL PRODUCTS

I

The invention relates to chemical-heat treatment of tool and structural steels of various classes and concerns liquid carburetors based on organic compounds for gas low-temperature nitro-carbonation at 5OO-65 ° C, which is desirable when processing the final cracked plaster and die tools.

A triethanolamine-based carburizer, containing water and activating additives of ammonium oxide, sodium nitrite and aluminate, introduced into triethanolamine in the form of saturated flj aqueous solutions, makes it possible to obtain wear-resistant layers with a carbon content of up to 0.7% and nitrogen. 0,2O%, firmly JQ associated with the base, not prone to chipping under dynamic loads, only at thicknesses of the layer not exceeding O, O6-O, O8 mm.

However, the main range of application of this carburizer is 7OO-95O C, the pyrolysis process is stabilized by the action of high temperature. In the temperature range of 56 ° –6OO ° C, the pyrolysis of triethanolamine, despite the introduction of x-containing additives, is not so complete as to ensure a stable amount of carbon monoxide in the furnace atmosphere, which is the main source of carbon for diffusion.

The aim of the invention is to intensify the saturation process, improving the wear resistance of the diffusion layer.

The goal is achieved in that ammonium acetate, ammonium and nickel nitrate are added to a known carburizer containing triethanolamine and water in the following ratio of components, wt.%:

Ammonium acetate 2.5-6.0 Ammonium nitrate 3, O-10, O Nickel nitrate 0.5-1.2

Water1.0-12.0

Triethanolamine Else.

The introduction of nitric acid and ammonium acetate into triethanolamine reduces the temperature at which the most complete and rapid decomposition of the main component of triethanolomine occurs to 49050 ° C, and the rate and completeness of pyrolysis, determined by the yield of active gases, increases by 30-80% compared to the known.

The catalytic effect of nickel nitrate is manifested in the process of its thermal dissociation above 5OO С - 2 N4 (N0 ,, :). 2 - 2 N-i 4N02 02

with the formation of nickel oxide, one of the main accelerators of carbon monoxide formation, due to the fact that the heat of formation of nickel oxide is very insignificant compared to the heat of formation of other oxides and is only 58.3 cal / g-mol. In addition, the resulting nickel oxide particles affect the binding of hydrogen to the molecular form: which prevents the occurrence of increased brittleness in the surface layer of the tool to be treated. The carburizer is prepared by sequential introduction of saturated aqueous solutions of ammonium nitrate MI NO, ammonium acetate ammonium CIH2NI and nickel nitrate Ni (NOjl-j.) To pure triethanolamine. chemically pure, acetic acid ammonium introduced as containing 14OO-.

1480 g / l of an aqueous solution, nickel nitrate in the form of an aqueous solution containing 23OO2350 g / l. The maximum amount of water injected with saturated aqueous solutions did not exceed 12%.

Example. Subjected to carbonitriding at 57 ° C for 3 hours in furnace 11–25 countersinks from steel R9K5, which have, after quenching and tempering, 5. The composition of the carburizer, wt.%

Acetic ammonium6.0

Ammonium Nitrate 10

Nickel nitrate1 2

Water7,5

Triethanolamine Else.

Carburizer consumption in the first

20 minutes is 138 cm V4, and then 156 cmH. Cool down the air. Saturation rate is 0.03 mm.

against 0.015 mm / h in a known carburizer. A layer with a depth of 0.101 m with a microhardness of 1007 kgf / mm / is obtained, while, during processing in a known carburizer, the depth of the layer is 0.056 mm. The wear resistance of the layer increased 1.5 times.

PRI mme R 2. Subjected to carbonitization in the furnace C-25 cutting tool of steel P 6M5 at 560 ° C for 4 hours. Carburizer consumption 145152 in the following compositions, wt.%:

Iqs

Acetic acid

ammonium2.53.0 6.0

NITRATE

ammonium .35.05 10.0

Nitrate

nickel 0.50.8 1.2

Water1,07,5 12,0

Triethanolamine Rest Ostal-Rest

According to the metaldographic analysis, the depth of the layer was 0.13 mm for 1 composition, 0.11 mm for P composition, 0.12 mm for W composition, O, 21 mm, 0.18 mm and 0, according to chemical layer-by-layer analysis, 19 mm respectively against 0, O7-O, O8 mm (by metallographic analysis) in a known carburizer. At the same time, the saturation rate of the layer in all compositions was almost the same - O, O4-0, O5 mm / h. The microhardness of the layer was H25-98O-1OO8kgs / dl 1 composition, H ,, 931-976 kgf / mm for 2 composition, 956-999 kgf / mm for III composition. The wear resistance of the layer increased 1.5-2 times.

The proposed carburizer increases the rate of formation of a layer with an optimal ratio of nitrogen and carbon on the tool by 1.5-1j / fold, while the wear resistance of the instrument increases 1.4-2, O times. Singes are not prone to chipping during shock. loads and with significant thicknesses 0,2-O, 25 mm. The carburizer is simple to prepare, does not contain deficient and toxic components, does not form carbon black resin compounds in treatment systems and systems for removal of gaseous products from furnaces.

Claims (1)

1. USSR author's certificate No. 524859, n. C 23 C 9/16, 1976.