SU912772A1 - Pulverulent composition for titanium zinc-chromizing steel and cast iron products - Google Patents

Description

one

This invention relates to a composition for the chemical heat treatment of metals and may find application in chemical industry for the anticorrosive protection of ferrous metals of carbon steel, cast iron, low alloy steels).

The known composition {l} for titanium-chromate of ferrous metals, containing powdered titanium dioxide, chromium oxide, aluminum, aluminum fluoride and aluminum oxide in the following ratio of components,

weight.

Titanium dioxide

Chrome oxide

Aluminum

Aluminum fluoride

Rest

Aluminum oxide

Also known is the composition for titanium-chromium ferrous metals, containing in the form of titanium powder, chromium, alumina, ferrochrome and ammonium iodide in the following ratio of components, wt.%; Titan3-20

Chrome 40 Aluminum oxide 8-25

Ferrochrom30

Ammonium iodide in 2 A disadvantage of the known compositions is the low corrosion and erosion resistance of ferrous metals,

10 protected by a known composition, in concentrated saline media, for example, in salt solutions. The purpose of the invention is to increase the corrosion and erosion resistance

ts

10-15 ferrous metals in concentrated

23-26 saline environments.

9-27

This goal is achieved by the fact that the composition for titanium-chromium coating in powder mixtures, containing titanium, chromium, alumina and ammonium halide, additionally contains molybdenum and boron in the following ratio of components, wt.%: 51.5 - 64.0 17.5 - 24.0 15.0 - 21.25 Alumina alumina Ammo) 1 salt of the molybdenum halide Additional addition to the composition of molybdenum allows to increase the passivating ability of diffusion time and eliminate pitting corrosion in concentrated salt media containing a high percentage of chlorides at 55-104. The introduction of boron having an atomic diameter of 0.91 A and a stronger carbide-forming element compared to chromium provides a more solid and ductile layer (due to the compaction of the diffusion layer and the adjacent base), which improves the erosion resistance of metals. The proposed ratio of the components is optimal, since only within the specified limits is corrosion and erosion resistant to ferrous metals in concentrated salt media. Moving beyond the limits of decreasing the number of components to be injected leads to the formation of punctate (pitting corrosion of the coating in concentrated saline environments at 55-104 ° C), going beyond the limits of increasing may disrupt the structure of the diffusion layer, resulting in the continuity and elasticity of the coating. The initial components included in the proposed composition have the following physical properties, titanium - metagsha 1 dark gray gray porous, chromium - silver metal powder, aluminum oxide - white orc, density 3.96 g / cm t ammonium halide is a white crystalline substance, molybdenum is a light gray metallic powder, boron is a black and gray metallic powder Composition dp titanokhroshivaniya is produced by preparing a mechanical mixture consisting of: out of 7080 wt.% titanium and 25-30 wt.% chromium. 75-80 wt.% (51.5-64 wt.% titanium and 17.5-24.0 wt.% chromium) are taken from the titanium-chromium mixture. and 0.75-1.5 wt.% molybdenum, 1.02, 0 wt.% boron, 15-21.25 wt.% alumina, 1.5-2.0 wt.% ammonium chloride are added to it. carefully mixing t. The process of diffusing titanium and chrome-plated ferrous metals with the proposed composition is carried out in a container-, pax at 1100-950 0. The duration of the diffusion saturation depends on the required depth of the protective layer and is 2-8 hours. P r and mer 1. Take 75 wt.% Tyrant , 28 wt.% Chromium and stirred. To 75% of the obtained titanium-chromium mixture, containing 51.5% by weight of titanium and 24.0% by weight of chromium, are added, by weight,%: molybdenum 1.5, boron I, ammonium chloride 2 and alumina 20 - and mix well. The composition is then transferred to a hermetically sealed box (stainless steel container). The composition is placed parts from cast iron and image-. The witnesses and the clerk are hermetically sealed. Then {tsik is heated in a chamber furnace to 950-1000 ° C and kept at this temperature for 8 hours. . After this, the box with the composition and cast-iron part is cooled in air. For a specified time, a diffusion of titanium-chrome layer with a thickness of 0.10-0.12 mm is obtained on the surface of the cast-iron part. Example 2, 78% by weight of titanium and 22% by weight of chromium are stirred, 0.75% by weight of molybdenum is added to 80% by weight of the resulting titanium-chromium mixture containing 62.4% by weight of titanium and 17.6% by weight of chromium , 1.5 wt.% Boron, 1.5 wt.% Ammonium chloride and weight,% alumina. The components are mixed and the resulting composition is transferred to a hermetically sealed box (coiteiner) made of stainless steel. Parts are made from cast iron and specimens are witnesses, and the VCD is hermetically sealed. Then, in a chamber furnace, the boxman is heated to a temperature of 950 ° C1000 and kept at this temperature for 4 hours. Thereafter, the box with the composition and the cast-iron part is cooled in air. In a specified time, a semi-diffusion titanochromic layer with a thickness of 0.05 to 0.07 mm is on the surface of the cast-iron part. Example 3, 76% by weight of titanium and 24% by weight of chromium are taken and mixed. To 79% by weight of the obtained titanium dye mixture containing 54.75 of titanium and 20.25% by weight of chromium, 1.5% by weight are added molybdenum, 2.0 wt.% boron, 1.5 wt. D ammonium chloride and 20.00 wt.% alumina. The components are mixed and the resulting composition is transferred to a hermetically sealed stainless steel box. The cast iron parts are placed in the composition and the witnesses and the box are sealed in samples. The box is then heated in a chamber furnace to 950-1000 ° C and kept at this temperature for 6 hours. Thereafter, the box with the composition and cast iron parts

cooled in air. During this time, a diffusion titanochrome layer with a thickness from 0.070 to 0.10 mm is obtained on the surface of cast iron 1X parts.

Samples - Witnesses protected together with parts were tested for corrosion and corrosion resistance.

Comparative characteristics of the properties of coatings obtained by treating carbon steel and cast iron using the proposed and known titanium-chromium compounds are given

in tabl ..

Table 1

NaCB (305-310 g / l) temperature 20-25 ° С, NH4CE - 187 g / l NaCf - 76.5 g / l - 56 g / l temperature 55C NHi P - pNH4CB - 174 g / l NaCB - 80 g / l MANSOZ - 59 g / l 0.970 - 39 g / l Temperature 98 ° С

The continuity of the layer, determined by Walker's reagent

(KjFe (CN) + NaCB points per 1 cm 1,400

LZ-W

Not

Not

Claims (2)

No 1,100 1,080 79 As can be seen from the data of Table 1, the corrosion rate of samples protected by the proposed composition is 0.001-0.005 g / m .4, and the corrosion rate of samples protected by a known composition 2, 0.67-1.4, g / m h and the composition of UlO, 75-l, l. In addition, the continuity and plasticity of the coating is improved, characterized by a decrease in microhardness, which indicates a higher erosion resistance of ferrous metals. Claims Powder composition for titanium-chromium steel and cast iron products containing titanium, chromium, alumina and ammonium halide, 20 characterized in that, with the aim of increasing the corrosion and erosion resistance of parts in concentrated salt media, it additionally contains molybdenum and boron the following ratio of components, wt.%. Titanium 51.5 - 64.0 Chromium 17.5 - 24.0 Alumina 15.00- 21.25 Ammonium halogenide 1.5 - 2.0 Molybdenum 0.75- 1.50 Bor 1 - 2 Sources of information, accepted tye into account in the examination 1.Avtorskoe certificate of the USSR №443941, cl. C 23 C, 9/02, 1974. 2. Heat-resistant and heat-resistant coatings. Proceedings of the All-Union Conference on Heat-Resistant Coatings. L., Nauka, 1969, p. 173.