RU2005099C1 - Method for preparing articles of glass powder materials - Google Patents

Description

compared with samples of the same chemical and particle size distribution formed by the semi-dry (uniaxial) pressing method.

The goal is achieved only in the range of hydrostatic pressure 350-1500 MPa. At pressures of less than 350 MPa, molded preforms have low mechanical strength, and sintered products have reduced density, residual porosity, and low mechanical strength. An increase in pressure above 1500 MPa does not lead to a further increase in the mechanical strength of the billets and sintered products, and the shrinkage value remains practically unchanged.

The goal is achieved only in the range of the specific surface area of the original glass powder from 1000 to 3000 cm2 / g, in which the flowability of the glass powder and press powder obtained by technology 3 are comparable. If the specific surface is below 1000 cm / g, it is not possible to obtain a high-quality workpiece and a sintered product, and with a specific surface exceeding 3000 cm / g, the flowability of the powder begins to be noticeably inferior to the flowability of the press powder (Table 1).

With hydrostatic pressing, it is possible to obtain high-quality sintered material even for relatively low specific surface areas of the powder, since the large pressure applied comprehensively to the sample significantly reduces the effect of dispersion on the properties of the sintered material by achieving a high degree of compaction of the preform even for powders with a specific surface of the order of 1000 cm2 / g.

The properties were measured according to standard methods for bending strength of samples in the form of racks 50x4x4 mm in size, shrinkage coefficient for reducing the length of the rafters as a result of sintering, density by hydrostatic weighing, porosity by optical microscopy, specific surface area using the PSX-22 device, and powder flowability - by the rate of expiration of the powder through the calibrated hole after drying the powder for 1 h at 110 ° C.

Example 1. Synthesis of glass grade C25-2 was carried out at 1590 ° C in a 10-ton batch furnace. The melt was granulated by casting in cold water. Granule t

crushed in a ball mill to a specific surface of 3000 cm / g Zltgm powder was placed in paper tubes, sealed with 5 rubber sheaths and subjected to hydrostatic pressure of 350 MPa. The preform was sintered at 860 ° C for 1 h. After pressing, the samples had annealing strength; 0.5 MPa, and after barely heat treatment 51 MPa; the density after heat treatment was 2.10 g / cm, the porosity was 0.3%, and the shrinkage coefficient was 12%.

The values of the flowability V glass

15 composition С25-2 with different specific surface S (V of the press powder prepared according to technology 3, accepted for 1) are presented in Table. 1.

The values of the properties of the prototype and blanks and sintered samples in the form of piles for examples 1-11 are given in table. 2.

Examples 2-4. The samples of these examples were prepared by analogy with example 1, Pressing pressure values,

5 heat treatment temperatures and properties of the obtained materials are presented in table. 2. Each value given in Table 2 is the result of averaging measurements at no less than 10 bars.

0 EXAMPLES 5, 6. The procedure for obtaining samples is similar to that described above. Given in the table. 2 values indicate that the goal is achieved only in the specified pressure range

5 presses.

Examples 7-11. Data obtained at a fixed pressing pressure of 500 MPa and for powders of different specific surfaces, together with

The data in Table 1 indicate that the set-goal is achieved only in the specified range of the specific surface of the glass powder.

(56) 1. US Patent No. 3222150, cl. 65-18.

5 1965.

2. Ermolenko N.N. The effect of the particle size distribution of the glass powder on the sintering, crystallization, and material properties in the TI02 - BrO3 - CaO - SrO 0 PbO system. Sat Glass, glass, silicate materials, vol. 4, Minsk: Higher School, 1975, p. 25-31.

3.Kulkov A.I. The manufacture of miniature glass insulators. Sat Exchange of experience5 volume in the radio industry, 1979, No. 7. p. 23.

Table 1

P is the compression pressure;

S is the specific surface;

сЈз - bending strength of the workpiece;

Tc is the sintering temperature;

os - bending strength of the sintered sample;

d is the density;

a - porosity;

C is the content of unburned ligament;

Cus is the coefficient of shrinkage during sintering.

Claims (1)

The claims METHOD FOR PRODUCING PRODUCTS FROM GLASS POWDER MATERIALS by synthesis of glasses, granulation of the melt, grinding of granules and molding of products from glass powder and their heat treatment, characterized in that, in order to increase uniformity, mechanical strength, density of billets and sintered products, lowering the temperature of the specimen 2 , can, reduction of the coefficient of shrinkage1 during sintering, exclusion of organic After bonding, to ensure high flowability of dry glass powder, the granules are crushed to a specific surface of 1000 - 3000 cm2 / g, and the product is formed by hydrostatic pressing of the original glass powders at a pressure of 350 - 1500 MPa.