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Anti-oxidant coating of bolt of high-temperature steam valve of power generation unit and preparation method thereof

A technology of anti-oxidation coating and high-temperature steam, which is applied in the direction of coating, metal material coating process, liquid chemical plating, etc., can solve the problem of inability to form protection, achieve long-term service anti-oxidation performance, and the cost of preparation The effect of low cost and simple preparation process

Active Publication Date: 2020-10-30
XIAN THERMAL POWER RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for bolts made of carbon steel, or stainless steel and nickel-based alloys with low Cr, Al, and Si contents, protective Al2O3, SiO2 and Cr2O3 films can only improve the high temperature oxidation resistance of metal materials through surface modification

Method used

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  • Anti-oxidant coating of bolt of high-temperature steam valve of power generation unit and preparation method thereof
  • Anti-oxidant coating of bolt of high-temperature steam valve of power generation unit and preparation method thereof
  • Anti-oxidant coating of bolt of high-temperature steam valve of power generation unit and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The anti-oxidation coating is prepared on the thread of 25Cr2MoV material, and the operation method is as follows:

[0028] 1) Use hot alkaline solution or organic cleaning agent to remove the grease on the surface of the bolt to expose the metallic luster;

[0029] 2) Carry out surface shot peening treatment on the cleaned bolts. The shot peening treatment uses cemented carbide shot with a diameter of 0.2mm, the shot peening pressure is 0.5MPa, the holding time is 10min, and the surface grain fragmentation depth after shot peening is 30μm ;

[0030] 3) Preheat the bolts after shot peening, and the preheating temperature is 85℃;

[0031] 4) Immerse the preheated bolt as a whole in a plating solution to prepare a nickel-yttrium coating. The temperature of the plating solution is 84° C. and the holding time is 12 hours; the plating solution is a mixed solution of nickel sulfate, yttrium sulfate, sodium hypophosphite, sodium acetate, sodium citrate and sodium dodecyl sul...

Embodiment 2

[0035] The anti-oxidation coating is prepared on the thread of 25Cr2MoV material, and the operation method is as follows:

[0036] 1) Use hot alkaline solution or organic cleaning agent to remove the grease on the surface of the bolt to expose the metallic luster;

[0037] 2) Carry out surface shot peening treatment on the cleaned bolts. The shot peening treatment uses cemented carbide shot with a diameter of 0.2mm, the shot peening pressure is 0.5MPa, the holding time is 10min, and the surface grain fragmentation depth after shot peening is 30μm ;

[0038] 3) Preheat the bolts after shot peening, and the preheating temperature is 80℃;

[0039]4) Immerse the preheated bolt as a whole in a plating solution to prepare a nickel-yttrium coating. The temperature of the plating solution is 84° C. and the holding time is 12 hours; the plating solution is a mixed solution of nickel sulfate, yttrium sulfate, sodium hypophosphite, sodium acetate, sodium citrate and sodium dodecyl sulf...

Embodiment 3

[0043] The anti-oxidation coating is prepared on the thread of 25Cr2MoV material, and the operation method is as follows:

[0044] 1) Use hot alkaline solution or organic cleaning agent to remove the grease on the surface of the bolt to expose the metallic luster;

[0045] 2) Carry out surface shot peening treatment on the cleaned bolts. The shot peening treatment uses cemented carbide shot with a diameter of 0.2mm, the shot peening pressure is 0.6MPa, the holding time is 10min, and the surface grain fragmentation depth after shot peening is 32μm ;

[0046] 3) Preheat the bolts after shot peening, and the preheating temperature is 82℃;

[0047] 4) Immerse the preheated bolt as a whole in a plating solution to prepare a nickel-yttrium coating. The temperature of the plating solution is 82° C. and the holding time is 15 h; the plating solution is a mixed solution of nickel sulfate, yttrium sulfate, sodium hypophosphite, sodium acetate, sodium citrate and sodium dodecyl sulfate...

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Abstract

The invention discloses an anti-oxidant coating of a bolt of a high-temperature steam valve of a power generation unit and a preparation method thereof. The anti-oxidant coating which is prepared from22-30% by mass of aluminum, 8-15% by mass of nickel, 2-6% by mass of chromium, 0.01-0.05% by mass of yttrium and the balance bolt base metal alloy elements is prepared on the surface of the bolt. Thepreparation method comprises the specific steps of first, carrying out shot blasting and preheating treatment at 80-85 DEG C on the bolt subjected to surface deoiling, derusting and cleaning; then, immersing the preheated bolt integrally in a plating solution at 80-85 DEG C for 10-15 hours; and finally, embedding the bolt with a plating layer in mixed powder for thermal diffusion treatment at 850-950 DEG C for 4-10 hours to obtain a 10-20 [mu]m thick aluminum-nickel-chromium-yttrium coating. The anti-oxidant coating disclosed by the invention is suitable for various bolts of a steam turbine.The bolts are made from CrMoV serial low alloy bolting steel, 12% Cr serial martensite bolting steel, nickel-based high-temperature alloy bolts and the like. The anti-oxidant coating disclosed by theinvention is simple in preparation flow and low in preparation cost, needs not to be machined subsequently and is obvious in oxidation resistance during long-term service.

Description

technical field [0001] The invention belongs to the field of surface engineering, and in particular relates to an anti-oxidation coating for a high-temperature steam valve bolt of a generator set and a preparation method thereof. Background technique [0002] The high-temperature steam valve is a part of the generator set that works under high temperature and stress conditions for a long time to fasten the connection or seal. , No leakage occurs, which plays a vital role in the normal operation of the high-temperature fastening parts of the power plant and the safety of the equipment. Generally speaking, the bolts used in the high temperature environment in the generator set include high pressure main steam valve bolts, medium pressure main steam valve bolts, high pressure speed regulating steam valve bolts, medium pressure speed regulating steam valve bolts, superheater safety door bolts, high pressure steam valve bolts, etc. Air duct flange bolts, high pressure inner cyli...

Claims

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Application Information

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IPC IPC(8): C23C18/50C23C18/18C23C10/56
CPCC23C18/50C23C18/1844C23C10/56
Inventor 鲁金涛周永莉杨珍黄锦阳严靖博党莹樱袁勇谷月峰
Owner XIAN THERMAL POWER RES INST CO LTD