Method for compactly sintering chromium oxide aggregate

A chromium oxide and aggregate technology, applied in the field of chromium oxide aggregate dense sintering, can solve the problems of flue gas pollution, difficult to control oxygen partial pressure, large energy consumption, etc. consumption effect

Inactive Publication Date: 2010-02-10
XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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AI Technical Summary

Problems solved by technology

[0007] 2. Controlled atmosphere sintering: P.D.Ownby and Junquist use controlled CO/CO 2 The ratio of the oxygen partial pressure of the sintering system is strictly controlled (in Cr 2 o 3 equilibrium oxygen partial pressure), so that pure Cr 2 o 3 The density after sintering reaches 98% of the relative density; however, the partial pressure of oxygen in the sintering process is difficult to control and can only be used in laboratory research, which is not conducive to industrial production
[0008] 3. Buried carbon sintering and composite buried layer sintering: Japan's Yamaguchi Akiyoshi and others adopted the method of buried carbon sintering, and sintered a

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  • Method for compactly sintering chromium oxide aggregate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Using pure Cr 2 o 3 Fine powder, press molding under 150MPa pressure, put into electric heating kiln, keep the pressure in the furnace greater than atmospheric pressure and not greater than 0.2atm (or keep the pressure in the furnace within the safe production range), sinter in Ar+CO atmosphere, control the kiln The partial pressure of CO in the furnace (p(CO)=0.0434atm), in the CO atmosphere maintained by carbon, sintered to obtain dense Cr 2 o 3 aggregate.

[0028] The specific operation is as follows: when sintering, first vacuumize the kiln, and fill in a proper amount of mixed gas of Ar and CO, so that the sintering furnace is in a closed state, and the pressure in the furnace is controlled not to exceed a certain value of 0.2atm. The sample is sintered at 1550°C and kept at this temperature for 2 hours to obtain a dense sintered sample. In the comparative example, the same sample was sintered at 1800°C for 3 hours in an air atmosphere (see ZL200510107260.X). ...

Embodiment 2

[0032] Using pure Cr 2 o 3 Micro-powder, press molding under 150MPa pressure, and put into electric heating kiln. Keep the pressure in the furnace not greater than 0.2atm, sinter in an Ar+CO atmosphere, control the CO partial pressure in the kiln (p(CO)=0.155atm), and sinter in a CO atmosphere maintained by carbon to obtain dense Cr 2 o 3 aggregate.

[0033] The specific operation is as follows: when sintering, first vacuumize the kiln, fill in an appropriate amount of Ar and CO mixed gas, the sintering furnace is in a closed state, and control the total pressure in the furnace to not exceed 0.2 atm. The sample is sintered at 1600°C and kept at this temperature for 2 hours to obtain a dense sintered sample. The bulk density and apparent porosity of the sintered samples are compared in Table 2.

[0034] Table 2

[0035] Bulk density / g·cm -3

Embodiment 3

[0037] Using Cr 2 o 3 Composite micropowder, its raw material composition (by mass percentage) 95% Cr 2 o 3 Fine powder, 5% nano Al 2 o 3 Micropowder, pressed at 150MPa and then loaded into an electric heating kiln, keeping the pressure in the furnace not greater than 0.2 atm, controlling the partial pressure of CO in the kiln (p(CO) = 0.081 atm), and sintering in a carbon-maintained CO atmosphere to obtain densification High chromium aggregate.

[0038] The specific operation is as follows: vacuumize first during sintering, and then fill with Ar+CO mixed gas. The sintering furnace is in a closed state, and the pressure in the furnace is controlled to be no more than 0.2 atm. Sinter at a temperature of 1500°C and keep at this temperature for 2 hours to obtain a dense sintered sample. The bulk density and apparent porosity of the samples after sintering are shown in Table 3.

[0039] table 3

[0040] Bulk density / g·cm -3

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Abstract

The invention discloses a method for compactly sintering a chromium oxide aggregate. The method comprises the following steps: after pressing and forming pure Cr2O3 micro powder or Cr2O3 compound micro powder, putting into an electric heating kiln or a heater type kiln, keeping the total pressure in the kiln, controlling CO differential pressure in the kiln and reducing and sintering a Cr2O3 material in a CO atmosphere maintained by carbon; firstly, vacuumizing when sintering, then filling Ar gas or Ar+CO gas of a protective gas, sintering at the temperature of 1400-1600 DEG C, keeping the temperature for 2 hours at the temperature and obtaining the pure Cr2O3 aggregate which is compactly sintered. The method has low labor strength, convenient and controllable sintering, low sintering temperature, environmental protection and energy saving, is safer than a method adopting an H2 atmosphere for sintering and is a good method for compactly sintering the aggregate with high chromium.

Description

technical field [0001] The invention belongs to the technical field of sintering of high chromium refractories, and relates to a method for dense sintering of chromium oxide aggregates. The method adopts an electric heating method and is densely sintered in a lower sintering temperature and a CO reducing atmosphere to obtain pure chromium oxide aggregates. or high chromium aggregate. Background technique [0002] Texaco coal gasifier can use low-grade coal such as coal slime and lean coal produced by coal preparation to produce industrial gas such as fertilizers and city gas. It is a key equipment for comprehensive utilization of coal with high efficiency and low pollution. Alkali-free glass fiber is mainly used for fiber reinforced materials, which can improve my country's international competitiveness in the field of new materials. High-chromium refractories are irreplaceable high-grade refractories for coal gasifiers and alkali-free glass fiber tank kiln linings, but the...

Claims

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Application Information

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IPC IPC(8): C04B35/66C04B35/64C04B35/12
Inventor 钱跃进蒋明学冯秀梅
Owner XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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