A kind of alloy surface coating and preparation method thereof

Abstract

The invention discloses an alloy surface coating. Through the steps of surface pretreatment, permeating agent pack cementation treatment, alkali washing, high-temperature carbonization and the like, a coating with stable performance can be formed on the surface of alloy, and the coating can effectively improve the anti-coking and anti-carburizing performance of the alloy and obviously prolong the decoking period and the service life of the material. The coating and a forming process thereof are especially suitable for high-temperature alloy and are especially used for high-temperature alloy of hydrocarbon raw material cracking furnace tubes.

Description

technical field

[0001] The invention belongs to the field of materials and material processing, and in particular relates to a surface coating of an alloy (especially a superalloy used for cracking furnace tubes of hydrocarbon raw materials) and a preparation method thereof. Background technique

[0002] The cracking of hydrocarbon feedstocks (ie, hydrocarbon feedstocks) is the most important route for the production of ethylene. Superalloys for cracking furnace tubes usually contain a large amount of Fe and Ni elements, and Fe and Ni elements will catalyze the growth of coke during the cracking process of hydrocarbon raw materials, resulting in a significant increase in the coking rate, a significant increase in heat transfer resistance, and a decrease in olefin production and yield. Rate. At the same time, these elements can also cause severe carburization of the furnace tube, which significantly shortens the service life of the furnace tube. Therefore, it is urgent to m...

Examples

Embodiment 1

[0024] After degreasing and derusting the HP40 alloy surface, put it into the seepage box together with the embedded infiltration agent (100 mesh powder). The composition of the infiltration agent is (by mass percentage): silicon powder 25%, chromium 50% 20% ferrochrome alloy, 3% ammonium chloride, 0.4% sodium fluoride, 0.2% cerium oxide, and the rest is high-temperature calcined Al2O3 powder. Put the sealed infiltration box into a muffle furnace and keep it warm at 950°C for 3h. Cool down to room temperature at a rate of 10°C / min, take out the seepage box, soak the alloy in 20% KOH aqueous solution, wash it with deionized water, and dry it. Subsequently, the alloy is put into a tubular heat treatment furnace, and the mixed gas of 80% hydrogen and 20% methane is continuously passed into the heat treatment furnace. Heat up to 950°C at a heating rate of 15°C / min, keep the temperature for 10 hours, and cool to room temperature with the furnace after the heat preservation is over...

Embodiment 2

[0028] After degreasing and derusting the surface of HK40 alloy, put it into the seepage box together with the embedding penetrating agent (200 mesh powder). , 3% ammonium chloride, 0.4% sodium fluoride, 0.2% cerium oxide, and the rest is high-temperature calcined Al2O3 powder. Put the sealed infiltration box into a muffle furnace and keep it warm at 1000°C for 2h. Cool down to room temperature at a rate of 10°C / min, take out the seepage box, soak the alloy in 20% KOH aqueous solution, wash it with deionized water, and dry it. Subsequently, the alloy was put into a tubular heat treatment furnace, and the mixed gas of 60% argon, 10% hydrogen and 30% methanol was continuously passed into the heat treatment furnace. Heat up to 950°C at a heating rate of 15°C / min, keep the temperature for 10 hours, and cool to room temperature with the furnace after the heat preservation is over, and stop the ventilation.

[0029] A uniform and dense coating is formed on the surface of the alloy...

technical field

[0001] The invention belongs to the field of materials and material processing, and in particular relates to a surface coating of an alloy (especially a superalloy used for cracking furnace tubes of hydrocarbon raw materials) and a preparation method thereof. Background technique

[0002] The cracking of hydrocarbon feedstocks (ie, hydrocarbon feedstocks) is the most important route for the production of ethylene. Superalloys for cracking furnace tubes usually contain a large amount of Fe and Ni elements, and Fe and Ni elements will catalyze the growth of coke during the cracking process of hydrocarbon raw materials, resulting in a significant increase in the coking rate, a significant increase in heat transfer resistance, and a decrease in olefin production and yield. Rate. At the same time, these elements can also cause severe carburization of the furnace tube, which significantly shortens the service life of the furnace tube. Therefore, it is urgent to m...

Examples

Embodiment 1

[0024] After degreasing and derusting the HP40 alloy surface, put it into the seepage box together with the embedded infiltration agent (100 mesh powder). The composition of the infiltration agent is (by mass percentage): silicon powder 25%, chromium 50% 20% ferrochrome alloy, 3% ammonium chloride, 0.4% sodium fluoride, 0.2% cerium oxide, and the rest is high-temperature calcined Al2O3 powder. Put the sealed infiltration box into a muffle furnace and keep it warm at 950°C for 3h. Cool down to room temperature at a rate of 10°C / min, take out the seepage box, soak the alloy in 20% KOH aqueous solution, wash it with deionized water, and dry it. Subsequently, the alloy is put into a tubular heat treatment furnace, and the mixed gas of 80% hydrogen and 20% methane is continuously passed into the heat treatment furnace. Heat up to 950°C at a heating rate of 15°C / min, keep the temperature for 10 hours, and cool to room temperature with the furnace after the heat preservation is over...

Embodiment 2

[0028] After degreasing and derusting the surface of HK40 alloy, put it into the seepage box together with the embedding penetrating agent (200 mesh powder). , 3% ammonium chloride, 0.4% sodium fluoride, 0.2% cerium oxide, and the rest is high-temperature calcined Al2O3 powder. Put the sealed infiltration box into a muffle furnace and keep it warm at 1000°C for 2h. Cool down to room temperature at a rate of 10°C / min, take out the seepage box, soak the alloy in 20% KOH aqueous solution, wash it with deionized water, and dry it. Subsequently, the alloy was put into a tubular heat treatment furnace, and the mixed gas of 60% argon, 10% hydrogen and 30% methanol was continuously passed into the heat treatment furnace. Heat up to 950°C at a heating rate of 15°C / min, keep the temperature for 10 hours, and cool to room temperature with the furnace after the heat preservation is over, and stop the ventilation.

[0029] A uniform and dense coating is formed on the surface of the alloy...