Method for preparing high-performance cathode material for plasma ignition

Abstract

The invention provides a method for preparing a high-performance plasma ignition cathode material, which belongs to a powder metallurgy technique of silver based cathode composite material. The method adopts a discharge plasma sintering method and uses silver and rare earth oxide as raw materials to perform ball-mill mixing according to the mass ratio of the silver to the rare earth oxide of 99.9:0.1-85:15, and then performing powder sintering through a sieve with less than or equal to 200 meshes, wherein the sintering temperature is between 400 and 700 DEG C, and the pressure is between 30 and 50 MPa. Before the temperature is 100 DEG C lower than the sintering temperature, the heating rate is between 50 and 100 DEG C per minute; and after the temperature is 100 DEG C lower than the sintering temperature, the temperature is raised to between 400 and 700 DEG C at a rate of between 30 and 80 DEG C per minute, and keeping the temperature for 5 to 15 minutes. The method can prepare the high-performance plasma ignition cathode material with higher compactness, good electrical conductivity and heat conductivity, strong electron emissive power, and long service life which is obviously longer than the prior cathode material; and because the Ag-based composite material replaces the prior pure silver, the cost is reduced and the performance of an ignitor is improved.

Description

technical field

[0001] The invention belongs to powder metallurgy technology of silver-based cathode composite material, in particular adopts discharge plasma sintering (SPS) method to prepare silver-based cathode composite material with high electron emission performance and relatively long service life. Background technique

[0002] The ignition and stable combustion of large industrial pulverized coal boilers are traditionally achieved by burning non-renewable resources such as heavy oil or natural gas. limit. In recent years, plasma ignition technology has been widely used in the boiler start-up stage, low-load stable combustion stage and unit sliding stop stage of power plants to replace oil gun ignition to achieve the purpose of energy saving and efficiency enhancement. However, the currently widely used plasma igniter cathode materials are mostly carbon rods and pure silver. Although carbon rods have the advantages of high melting point and good electrical and therma...

Examples

Embodiment 1

[0014] Ball milled for 30min and the powder was sintered by spark plasma at 500℃

[0015] Raw materials: Ag powder (200 mesh, 99.99%) 32.4g, rare earth oxide 0.49g (La 2 o 3 : CeO 2 : Y 2 o 3 =1:1:3)

[0016] After the above-mentioned raw material powders are fully mixed, put them into a stainless steel ball mill tank, add steel balls and alcohol, the ball-to-material ratio is 10:1, and then start the ball mill with a three-dimensional vibrating high-energy ball mill, and stop it every 15 minutes during the process to cool down the temperature. Check the machine. After grinding, the powder and balls were separated, and the powder was dried in a vacuum oven (70°C, 24 hours), and then passed through a 200-mesh sieve. Then the powder is sintered by SPS, the size is φ20×10, the sintering process is as follows: sintering temperature 500°C, pressure 30Mpa. Before 400°C, the heating rate was 100°C / min, after 400°C, it was heated to 500°C at 30°C / min, and kept for 8 minutes.

Embodiment 2

[0018] Ball milled powder for 30min and spark plasma sintering at 600℃

[0019] Raw materials: Ag powder (200 mesh, 99.99%) 27.28g, rare earth oxide 3.03g (La 2 o 3 : CeO 2 : Y 2 o 3 =1:1:3)

[0020] After the above-mentioned raw material powders are fully mixed, put them into a stainless steel ball mill tank, add steel balls and alcohol, the ball-to-material ratio is 10:1, and then start the ball mill with a three-dimensional vibrating high-energy ball mill, and stop it every 15 minutes during the process to cool down the temperature. Check the machine. After grinding, the powder and balls were separated, and the powder was dried in a vacuum oven (70°C, 24 hours), and then passed through a 200-mesh sieve. Then the powder is sintered by SPS, the size is φ20×10, the sintering process is as follows: sintering temperature 600°C, pressure 40Mpa. Before 500°C, the heating rate was 100°C / min, and after 500°C, it was heated to 600°C at 50°C / min, and kept for 10 minutes.

Embodiment 3

[0022] The powder was ball milled for 720min and sintered by spark plasma at 700℃

[0023] Raw materials: Ag powder (200 mesh, 99.99%) 50g, rare earth oxide CeO 2 2.02g

[0024] After the above-mentioned raw material powders are fully mixed, put them into a stainless steel ball mill tank, add steel balls and alcohol, the ball-to-material ratio is 10:1, and then use a planetary ball mill to start ball milling for 12 hours. After grinding, the powder and balls were separated, and the powder was dried in a vacuum oven (70°C, 24 hours), and then passed through a 200-mesh sieve. Then the powder is sintered by SPS, the size is Φ20×15, the sintering process is as follows: sintering temperature 700°C, pressure 35Mpa. Before 600°C, the heating rate is 100°C / min, after 600°C, it is heated to 700°C at 70°C / min, and kept for 15 minutes.

[0025] Example results:

[0026] After the above experiments, the specific performance of the cathode material is measured as follows:

[0027] 1) ...

technical field

[0001] The invention belongs to powder metallurgy technology of silver-based cathode composite material, in particular adopts discharge plasma sintering (SPS) method to prepare silver-based cathode composite material with high electron emission performance and relatively long service life. Background technique

[0002] The ignition and stable combustion of large industrial pulverized coal boilers are traditionally achieved by burning non-renewable resources such as heavy oil or natural gas. limit. In recent years, plasma ignition technology has been widely used in the boiler start-up stage, low-load stable combustion stage and unit sliding stop stage of power plants to replace oil gun ignition to achieve the purpose of energy saving and efficiency enhancement. However, the currently widely used plasma igniter cathode materials are mostly carbon rods and pure silver. Although carbon rods have the advantages of high melting point and good electrical and therma...

Examples

Embodiment 1

[0014] Ball milled for 30min and the powder was sintered by spark plasma at 500℃

[0015] Raw materials: Ag powder (200 mesh, 99.99%) 32.4g, rare earth oxide 0.49g (La 2 o 3 : CeO 2 : Y 2 o 3 =1:1:3)

[0016] After the above-mentioned raw material powders are fully mixed, put them into a stainless steel ball mill tank, add steel balls and alcohol, the ball-to-material ratio is 10:1, and then start the ball mill with a three-dimensional vibrating high-energy ball mill, and stop it every 15 minutes during the process to cool down the temperature. Check the machine. After grinding, the powder and balls were separated, and the powder was dried in a vacuum oven (70°C, 24 hours), and then passed through a 200-mesh sieve. Then the powder is sintered by SPS, the size is φ20×10, the sintering process is as follows: sintering temperature 500°C, pressure 30Mpa. Before 400°C, the heating rate was 100°C / min, after 400°C, it was heated to 500°C at 30°C / min, and kept for 8 minutes.

Embodiment 2

[0018] Ball milled powder for 30min and spark plasma sintering at 600℃

[0019] Raw materials: Ag powder (200 mesh, 99.99%) 27.28g, rare earth oxide 3.03g (La 2 o 3 : CeO 2 : Y 2 o 3 =1:1:3)

[0020] After the above-mentioned raw material powders are fully mixed, put them into a stainless steel ball mill tank, add steel balls and alcohol, the ball-to-material ratio is 10:1, and then start the ball mill with a three-dimensional vibrating high-energy ball mill, and stop it every 15 minutes during the process to cool down the temperature. Check the machine. After grinding, the powder and balls were separated, and the powder was dried in a vacuum oven (70°C, 24 hours), and then passed through a 200-mesh sieve. Then the powder is sintered by SPS, the size is φ20×10, the sintering process is as follows: sintering temperature 600°C, pressure 40Mpa. Before 500°C, the heating rate was 100°C / min, and after 500°C, it was heated to 600°C at 50°C / min, and kept for 10 minutes.

Embodiment 3

[0022] The powder was ball milled for 720min and sintered by spark plasma at 700℃

[0023] Raw materials: Ag powder (200 mesh, 99.99%) 50g, rare earth oxide CeO 2 2.02g

[0024] After the above-mentioned raw material powders are fully mixed, put them into a stainless steel ball mill tank, add steel balls and alcohol, the ball-to-material ratio is 10:1, and then use a planetary ball mill to start ball milling for 12 hours. After grinding, the powder and balls were separated, and the powder was dried in a vacuum oven (70°C, 24 hours), and then passed through a 200-mesh sieve. Then the powder is sintered by SPS, the size is Φ20×15, the sintering process is as follows: sintering temperature 700°C, pressure 35Mpa. Before 600°C, the heating rate is 100°C / min, after 600°C, it is heated to 700°C at 70°C / min, and kept for 15 minutes.

[0025] Example results:

[0026] After the above experiments, the specific performance of the cathode material is measured as follows:

[0027] 1) ...