Novel method for carrying out low-temperature surface catalysis and nitriding on alloy cast iron

A technology of alloy cast iron and surface catalysis, which is applied in the direction of metal material coating process, coating, solid-state diffusion coating, etc., can solve the problems of large deformation of parts, pore pitting, etc., achieve fast nitriding rate, promote diffusion, Effect of low nitriding temperature

Active Publication Date: 2010-11-10
SHANDONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the nitriding temperature of the alloy cast iron cylinder liner is above 510°C, the deformation of the parts is large, and defects such as pores and pitting are prone to occur.

Method used

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  • Novel method for carrying out low-temperature surface catalysis and nitriding on alloy cast iron
  • Novel method for carrying out low-temperature surface catalysis and nitriding on alloy cast iron
  • Novel method for carrying out low-temperature surface catalysis and nitriding on alloy cast iron

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Experimental program
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Effect test

Embodiment 1

[0026] Example 1 400℃×10h low temperature nitriding

[0027] Alloy cylinder liner composition (see Table 1), surface hardness: 220-280HB, tensile strength: 245MPA.

[0028] Table 1. Alloy cylinder liner composition

[0029]

[0030] Technical requirements: surface nitriding treatment, white bright layer greater than 6 microns, microhardness HV600-800.

[0031] The traditional nitriding temperature is 500-510°C, keep the temperature for 7 hours, and then cool down. After the cylinder liner is nitrided, it is polished once, and the product has polished pits, that is, pores. Now perform the following process: the cylinder liner is degreased, derusted, cleaned, dried, and put into the treatment liquid for treatment. The nitriding temperature is 400°C, the ammonia gas flow rate is 300-1000ml / min, the furnace pressure is 5-15mm water column, and the preset nitriding temperature is maintained for 10 hours. At the same time, turn on the hydrogen analyzer to detect the ammonia d...

Embodiment 2

[0032] Example 2 500℃×4h low temperature nitriding

[0033] The performance of the alloy cylinder liner is the same as above, and now the following process is carried out: the cylinder liner is degreased, derusted, cleaned, dried, and put into the treatment liquid for treatment. The nitriding temperature is 500°C, the ammonia flow rate is 800-1600ml / min, the furnace pressure is 6-10mm water column, and the preset nitriding temperature is maintained for 4 hours. At the same time, turn on the hydrogen analyzer to detect the ammonia decomposition rate. Record the ammonia decomposition rate every hour, and adjust the flow of ammonia gas to ensure that the ammonia decomposition rate is between 20% and 45%. After nitriding at 500℃×4h, the thickness of the compound layer is 20μm, the nitrided layer is 90um, and the surface microhardness is HV752.

[0034] From the above implementation results, the new nitriding process of this patent invention, the catalytic film prepared by surfac...

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Abstract

The invention relates to a novel method for carrying out low-temperature surface catalysis and nitriding on alloy cast iron, belongs to the technical field of the surface chemical heat treatment application of metal materials and is suitable for low-temperature and rapid surface nitrogen treatment (in the strengthening nitriding process, the temperature is less than 480 DEG C and the time is less than 10 hours; and in the corrosion-resisting nitriding process, the temperature is between 500 and 520 DEG C and the time is less than 4 hours) of an alloy cast iron cylinder sleeve and an alloy cast iron piston ring. Based on the surface catalysis theory, the invention designs an active catalyst component, utilizes an adjustable bidirectional pulse power supply to form a catalytic film, i.e. a surface catalyst, on the surface of the alloy cast iron, improves the activity that the metal surface carries out catalytic decomposition on ammonia at the low temperature and also effectively adsorbs the decomposed free nitrogen to form a nitrogen adsorption layer. Moreover, the catalyst can permeate into a substrate to form solid solution so as to promote the diffusion rate of nitrogen. Compared with the conventional gas nitriding method, the process increases a working procedure of adjustable bidirectional pulse surface deposition treatment. The working procedure has the advantages of stable conditioning fluid and short processing time. The novel process is suitable for the existing gas nitriding equipment.

Description

technical field [0001] The invention relates to a new method for catalytic nitriding of the low-temperature surface of alloy cast iron cylinder liners, which belongs to the technical field of chemical heat treatment application on the surface of metal materials, and is suitable for the low-temperature rapid nitriding treatment of the surfaces of alloy cast iron cylinder liners and piston rings. Background technique [0002] Nitriding, also known as nitriding, is the process of infiltrating active nitrogen atoms into the surface of steel parts. Nitriding changes the chemical composition and organizational state of the surface, thus changing the strength properties, friction properties and corrosion properties of steel materials under static load and alternating stress. Nitriding parts have the characteristics of high hardness, wear resistance, good fatigue resistance and small deformation, so they are widely used in machinery industry, petroleum industry, defense industry and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/02C23C8/26C25D5/18
Inventor 孙金全崔洪芝谢鲲张国松王积森陈蕴博
Owner SHANDONG UNIV OF SCI & TECH
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