SU1696575A1 - Composition of bath for low-temperature borosulfurizing - Google Patents

Abstract

The invention relates to metallurgy, as well as to compounds for chemical-thermal treatment of cast iron products, and can be used for processing cylinder liners of diesel engines. The aim of the invention is to improve the wear resistance and corrosion resistance of cast iron cylinder liners of diesel engines. The composition contains, by weight .%: water 43.0-45.0; caustic soda 47-49.0; sodium sulphide 0.9-1.1; sulfuric acid sodium 1.0-2.0; borax 5.0-6 , 0. This allows 1.7-1.9 times increase in wear resistance and 1.3-1.5 times the corrosion resistance of cast-iron cylinder liners of diesel engines compared to Prototype w. ,, yl 1 2 table.

Description

This invention relates to the chemical heat treatment of cast iron products and can be used in the processing of cylinder liners of diesel engines.

The aim of the invention is to increase the wear resistance and corrosion resistance of cast iron cylinder liners of diesel engines.

The drawing shows the curves characterizing the action of the proposed and known compositions

The composition contains, by weight,%:

Water

Sodium hydroxide

Sodium Sulfur

Sulphurous sour

sodium

Borax

Borosulphidae is as follows.

The parts previously treated in a 3-5% solution of sulfuric acid for 2-3 minutes are washed with running water and immersed in a bath, where they are aged 43, 0-45.0, 47-49.0 0.9-1 ,one

1.0-2.0 5.0-6.0 performed

they are 60-65 minutes at 150-155 ° C. Zatam their pro; wash with running water and dry.

Example 1. Comparative tests of cast iron samples of uncoated samples treated in a bath with a known composition and samples treated in the proposed composition at 155 ° C for 65 minutes are carried out. The tests are conducted on an SMTs-2 type friction machine according to the disc-block scheme. The discs and pads are made of single-alloyed alloyed steel SCh24-44. Samples prior to testing are hardened to a hardness of 600-680 Vickers. The roughness of the friction surfaces is determined every 2 hours of testing using a profilogram-profilometer of the VEI-201 model of the Caliber plant.

The wear of the discs is determined by weighing them after every 2 hours of testing on an analytical weigher of the type VLA-200 gM.

The tests on the SMC-2 friction machine are carried out in the following modes:

with

Os

Yu

about

SP

Vi ate

The disk load per roller is 10 MPa, the roller rotation frequency is 500 minutes, the test duration is b h, and the oil supply (MUG) to the friction disk surface is 8-10 drops per minute.

The load on a pair of friction is created using a special device that is available on the friction machine. The machine is started up when the load on the specimens is removed, after which, within 1.5-2 min, the load is smoothly adjusted to the set value.

In the course of all the tests on the lower shaft of the machine with the help of a special device, the moment of friction is measured and recorded continuously while recording on the tape of the potentiometer KSP-2-005,

Testing of specimens for sticking reveals the dependence of the moment of friction on the load, establishes the ultimate load at which the setting and tearing of the rubbing surfaces in the boundary friction mode occurs. Operating samples (after being tested on a friction machine) are loaded at 0.25 kN every 3 minutes.

The test results of iron samples are presented in table. 1 and in the drawing, where curve 1 characterizes the effect on samples of known composition, curve 2 - the proposed composition,

Example 2. Corrosion resistance tests are carried out at elevated relative humidity and temperature with periodic condensation of moisture and the introduction of an aggressive component — sulfur dioxide according to GOST.

Cast iron samples treated in the known and proposed formulations are subjected to tests. Samples (alloyed cast iron brand СЧ24-44) are weighed on an analytical balance of the type VLA-200 gM with an accuracy of 0.1 mg and placed in special cassettes. Then the samples are placed in a double-wall chamber and kept at 40 ° C for 8 hours at 100% relative humidity. Then the chamber is turned off and cooled to room temperature for 16 hours, the chamber door is opened at the same time, which reduces the humidity to 75%. Sulfur dioxide is introduced at the beginning of each cycle in the amount of 0.2 dm3.

After testing, the samples are thoroughly cleaned of corrosion products, for which they are placed in an electrolyte bath (8%

sodium hydroxide solution) and incubated for 20 min at 20 ° C. The parts are then air dried and weighed again. The values of the mass change of the samples are calculated by the formula

lt mo-mi

dt-

where is the initial mass, g;

mi is the sample mass after removal of corrosion products, g;

S is the surface area of the sample before testing, m.

In order to determine the index of non-uniformity of corrosion, tracing is applied to the cleaned surface of the cast-iron samples and a sketch is drawn of all the places covered with corrosion. The traced areas of tracing paper are cut out and weighed on an analytical balance. After that, knowing the mass of a unit of the area of tracing paper, calculate the area covered by corrosion and the index of non-uniformity of corrosion:

J5

Si

where I is the index of non-uniformity of corrosion; Si is the area occupied by corrosion, m2.

The results of tests for corrosion resistance are presented in table. 2

Thus, the use of the proposed composition of a low-temperature bath for chemical-heat treatment of parts increases their wear resistance by 1.7–1.9 times under steady state operation and 1.3–1.5 times by corrosion resistance, which allows to increase the vital a cycle of cylinder liners of diesel engines in operation, made of cast iron.

Claims (1)

Claims of the Invention Composition of a low-temperature borosulfidation bath, predominantly cast iron cylinder liners of diesel engines, containing water, caustic soda, sodium sulphide, sulfuric acid sodium, borax, characterized in that. in order to increase wear resistance and corrosion resistance, the components are taken in the following ratio, wt.%: Water43.0-45.0 Caustic soda 47,0-49,0 Sodium sulphide0.9-1.1 Sulphurous sour sodium1.0-2.0 Bura5.0-6.0 Н20 40.0-42.0 NaOH 42.0-44.0 S 0.9-1.1 Na2S 0.9-1.1 Na2StO, 1.0-2.0 NaiE4Or7.5-8.5 HBO, 5.0-6.0 KZ045,0 NaOH47 ,9 NaSa031 Na2B4035 HZ0 NaOH 44 48 Na2S Na2S703 1.5 NazE ,, Or 5.5  43 NaOH 49 1.1 NazS203 2.0 NazB407 6.0 431 670 0.18 405 670 .1.16 405 670 1.22 324 805 0.08 289 812 0.09 275 796 0.83 en CO o SL -J SL 326 805 0.08 296 309 0.09 288 799 0.63 335 780 0.10 302 800 0.21 295 794 0.71 CD Known composition 50,400 50,050 10-1 6.7-10 -four 350 1.49 The proposed composition 50,400 50,120 10-10 gz -44, 9-10, 230 2.04 sg with ABOUT) ate ate 50,400 50,130 10-10 -3 5.2 Ur4 270 1.92 50,49950,12210-10 34.9-U 42782.04 V l / J T / -her/- M 5o sc f 100 -(50 goo