RU1794915C - Binder - Google Patents

Abstract

It is used in the chemical industry, in non-ferrous metallurgy, in the manufacture of electrical contact parts, conductive putties and coatings operating in aggressive environments at elevated temperatures. It contains components in the following May ratio. %: phosphoric acid 60-65, filler - solid solution of silicon and titanium nitrides with a titanium content of 25-30, 35-40. In the preparation of the binder, the powdered filler is closed with phosphoric acid. The tensile strength is 56.1 MPa. Degree of decomposition in hydrochloric acid at 100 ° C 0.04, in phosphoric acid at 100 ° C 0.06. 1 tab.

Description

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The invention relates to compositions of electrically conductive corrosion-resistant binders and can be used in the chemical industry, in non-ferrous metallurgy, in the manufacture of electrical contact parts, conductive coatings and coatings operating in aggressive environments at elevated temperatures.

A known composition is astringent, including concentrated orthophosphoric acid (40.5-48.0 May.%) And an electrically conductive filler - highly dispersed titanium nitride (52.0-59.5 May.%) With a particle size of 0.05-0, 1 μm with a ratio of TM / P20b 1.5-2.0.

The disadvantage of the given astringent composition is its low resistance to liquid and gas aggressive media, and low thermal cyclicity (5-6 cycles).

Known composition of the binder, including phosphoric acid (until May 35.%), Molten particles of magnesium oxide (up to

May 10th. %), fibrous asbestos (up to 5%) and a powdery material having electrical conductivity (copper, silver) and high melting accuracy, such as titanium nitride, tungsten carbide, etc., up to May 60. %

The disadvantage of the composition under consideration is the low chemical resistance in aggressive environments, the decrease in the electrically conductive properties of the material at elevated temperatures (500 ° C) due to the oxidation of the electrically conductive filler.

It is also known in the burning prototype, which includes phosphoric acid (May 35-45.%) And titanium carbonitride (May 55-65.%) In the ratio, 22-1.85 (3). The temperature of cement hardening is 300-350 ° C, the electrical resistivity is 2 10 Ohm m. The number of thermal cycles (500-20 ° C) is 10, the mass loss of cement in HCI at 100 ° C is 0.11%, in NZRC at the same interaction temperature - 0.15%. Increase Specific Rotation VI

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of carbonitride to 33 m / g leads to a decrease in the T / W ratio to 0.93 and, as a result, reduces the electrical resistivity to 4-9 10 Ohm m.

A disadvantage of the specified composition in the mastic is a low chemical stability in aggressive media at elevated temperatures and low thermal cycling.

The purpose of the invention is to increase chemical resistance and mechanical strength.

The goal is achieved in that the binder, including orthophosphoric acid and an electrically conductive filler, contains as a filler a solid solution of silicon and titanium nitrides with a titanium content of 25-30% in the following ratio of components, May. %:

Phosphoric Acid 60-65

Solid nitrile solution

dov silicon and titanium

with content

titanium 25-30% 35-40

A solid solution of silicon and titanium nitrides are phases of variable composition of the general formula Sla-xTixN / j, in which part of the silicon atoms in SiaN4 are replaced by titanium atoms. At the same time, the material acquires the best properties of individual compounds: high chemical resistance and thermal cyclicity, characteristic of both better electrical conductivity and ductility of titanium nitride. It should be noted that the hardening effect is observed only when using ultrafine Si3-xTixN4, which causes its active-. relative to НзРОз in comparison with a coarse-grained compound of the same chemical composition.

With an increase in the silicon content in the solid solution, the chemical stability and strength of cements sharply increase, while its electrically conductive properties drop sharply. The curing temperature of cements, at which the metal acquires a set of necessary properties, increases by 50-100 ° C (depending on the concentration of silicon in the solid solution), which lengthens the hardening process and leads to an excessive consumption of electricity during the preparation of the binder. On the other hand, an increase in the titanium content in a solid solution leads to a decrease in the electrical resistance and chemical resistance of cement.

The invention makes it possible to obtain an electrically conductive corrosion-resistant cement at relatively low heat treatment temperatures. Previously solid solutions of titanium and silicon nitrides

no electroconductive, corrosion-resistant cements have been used to achieve this goal.

The sequence of operations when obtaining an electrically conductive corrosion-resistant cement is as follows:

A certain amount (20 g) of a solid solution consisting of silicon-titanium nitride (25-30%) is portionwise closed with concentrated phosphoric acid (d-1.74 g / cm3) to obtain a plastic mass.

The acid consumption is 60-65%, ratio 67-0.54.

The prepared mass is placed in fluoroplastic molds of 10x10x10 mm and subjected to heat treatment up to 350 ° C at a temperature rise rate of 20 deg / h.

After reaching the set temperatures, the system is cooled to room temperature, cubed samples are removed, and the physicochemical and mechanical properties of the hardened cement are examined.

Example 1. To obtain an electrically conductive corrosion-resistant binder, 20 g (40%) of a powdery substance (Si3-xTixN4) of a specific surface area of 55 m / n was taken by mixing it with 30 g (60%) concentrated orthophosphoric acid (d- 1.74 g / cm3) to obtain a plastic mass. A thoroughly mixed mass in the ratio T / G-0.67 is placed in fluoroplastic forms and heat treated in an oven to 350 ° C at a speed of 20 ° C / h. After reaching the set temperature, the system is slowly cooled to room temperature, cubed samples are removed from the molds and their physicochemical properties are examined. Electrical resistivity, Ohm - m386 Degree of decomposition of the sample at 100 ° C:. 0.05

In NZR04conc. 0.08

The number of thermal cycles (500-20 ° C) 15 The remaining examples are similar, but differ in the composition of the components and are presented in the table.

As follows from the data in the table, the use of a solid solution of Si3-xTixN4 as an electrically conductive filler leads (examples 1-7) to obtain corrosion-resistant in acids materials with increased heat resistance (15-20 cycles) compared to the prototype (6 -10 cycles). The data of examples 8-9 show that with transcendental

the values of acid and filler the properties of the synthesized samples change in different directions: for example, with an increase in the acid content (70%) and a decrease in the consumption of Sl3-xTlxN4 (30%), the electrical resistance sharply increases, the mechanical strength of the samples decreases, but their chemical resistance and thermocyclicity remains at a sufficiently high level. A decrease in acid consumption (55%) and an increase in the amount of filler reduces both the electrical resistance value (positive factor) and chemical resistance and thermal cycling (negative factors).

Thus, in the indicated ranges of the starting components used (examples 1-7), it is possible to obtain materials that comprehensively satisfy the objectives of the invention.

Claims (1)

When using a solid solution of titanium and silicon nitrides in the recommended Formula 25 An astringent, including orthophosphoric acid and a titanium-containing electrically conductive filler, characterized in that, in order to increase the chemical resistance and mechanical strength, it contains a solid solution of nitride nitrides as a titanium-containing filler. Production conditions and physicochemical properties of cement stone according to the invention. The flow rate of the solid solution is 20 g, the rate of temperature rise is 0.3 deg / min. NzRO / i - 85%. The specific surface area of the filler is 55 m / g. At wide intervals (35-40%), the content of the electrically conductive filler (TIN) in SlsN / j, which is characterized by high dielectric properties, is also of great importance. So, in example 10 it is clearly seen that a decrease in the titanium content in Si3-xT xN4 to 20% leads to an increase in the electrical resistance of the samples, while maintaining other properties according to invention. An increase in the titanium content in the solid solution is accompanied by both a decrease in the electrical resistance and the main characteristics of the cement stone (chemical resistance and thermal cycling). Therefore, this objective of the invention is achieved not only by the optimal interval between the liquid and solid components in the burning composition, but also from composition of the solid phase, as changes in the titanium content in the solid solution changes the basic properties of the composition. tan and silicon - with a titanium content of 25-30% in the following ratio of components, May. %: Phosphor Acid 60-65 Solid solution of silicon and titanium nitrides with a titanium content of 25-30% 35-40