CN1119432C

CN1119432C - Salt-bath low-temp. electrolytic sulfurizing for steel-iron components

Info

Publication number: CN1119432C
Application number: CN97117231A
Authority: CN
Inventors: 张志乾
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-08-26
Filing date: 1997-08-26
Publication date: 2003-08-27
Anticipated expiration: 2017-08-26
Also published as: CN1209467A

Abstract

The present invention belongs to an electrochemical treatment technology for the surface of ferrous metal. A large quality of indissolvable substances, namely residue, is continuously generated in a low-temperature electrolytic sulfurizing process of a salt bath so that the salt bath is aged. The inventor discovers that the residue contains magnetic materials and nonmagnetic materials. In the present invention, magnetic residue is extracted out in time, and nonmagnetic residue is converted into magnetic residue by an adding technology. Thus, the total residue content in the salt bath is maintained within 2.0%, the magnetic residue content is maintained between 0.2 and 1.0%, the nonmagnetic residue content is less than 1.0%, and the salt bath is not aged for a long time and lies in a high-activity state. The method of the present invention mainly uses old recovered salt, has few dosages of new salt and has no existence of the phenomena of accumulation and abandonment caused by excessive old salt.

Description

The salt-bath low-temp electrolysis sulfurizing of steel-iron components

The present invention's (salt-bath low-temp electrolysis sulfurizing of steel-iron components) belongs to the surface electrochemistry treatment technology of ferrous metal.Its effect is to generate one deck sulfurized layer on the steel-iron components surface.This layer has excellent anti scuffing and antistick ability, and makes frictional coefficient reduce 1/3-2/3, and the result increases substantially the wear resistance of part.

The present invention is the significant improvement to existing salt-bath low-temp electrolysis sulfurizing technology.

The disadvantage of salt-bath low-temp electrolysis sulfurizing technology is that salt bath is easily aging.The main reason of aged is insolubles---the slag in the salt bath.When slag content surpasses 2.5-3.0%, promptly begin to wear out.

French Patent " surface treatment method of ferrous metal " adopts the method for continuous filtration that the slag of particle in the salt bath greater than 10 μ filtered out, and slag content is maintained below 2.5%.(" metal heat treatmet " 1986, No2 P9-16) utilize 50% new salt+50% to reclaim salt+S " the active research of low-temperature electrolytic sulfurizing salt bath " _XMethod, reduce the formation speed of slag, improve beginning aged slag content, to prolong the life-span of salt bath.

Because the formation speed of slag is very fast in the sulfurizing process, so filtering workload is very big, again with the expensive filter plant of a cover; New and old (recovery) salt half-and-half adds S again _XThough, can prolong the salt bath life-span, very limited.This not only will often change and all use salt, and new salt consumption is big, and a large amount of old salt of very fast accumulation are only scrapped because of have more than is needed.Resultant costs is too high, can't industrial application.

In application and research to salt-bath low-temp electrolysis sulfurizing, the inventor finds following and important phenomenon:

Slag generates or formation speed is very low if do not have in 1, the sulfurizing process, just sulfurizing can not normally be carried out.When the salt bath activity is best, when living slag speed also is the highest.

2, the insolubles-slag that produces in the salt bath in the sulfurizing process be magnetic and non magnetic not, or more precisely slag have can be adsorbed by permanent magnet and be difficult for being adsorbed not; The magnetic slag particle is trickle, and non magnetic solid impurity particle is thick; The magnetic slag formation speed is much larger than non magnetic slag; Magnetic slag and non magnetic slag can transform mutually.

3, two kinds of slags all influence the activity of salt bath.No matter magnetic slag content is many and few, the non magnetic quantity of slag was greater than 1.0% o'clock active variation of salt bath; Magnetic slag＜0.2% activity is also poor, and＞1.0% o'clock to non magnetic slag conversion aggravation, active can sharply the decline.In order to guarantee the high reactivity of salt bath, total quantity of slag does not want＞2.0%.

4, add new salt in salt bath, coarse grained non magnetic slag can be refined into the magnetic slag of diameter less than 10 μ very soon.

Based on above important discovery, the inventor adopts following measure to receive and good effect: the salt bath activity can be adjusted simply and easily at any time, keeps high reactivity muchly, and the sulfurizing process controllably is under the standard state.Its method is:

1, the salt bath proportioning is the recovery salt that the new salt of 6-15% adds 94-85%.New and old salt proportioning does not need 1: 1.Saved a large amount of new salt like this, made full use of old salt, eliminated old salt and piled up and large quantities of phenomenon of scrapping.

2, as shown in drawings, make a non-leakage box 1 with stainless steel plate, in fill polylith 500-1200 Gauss's permanent magnet 2.This box was placed 170-200 ℃ of salt bath 10-45 minute, take out magnetic slag and adherent salt that water washes away the outer absorption of box then.Thresh several times, the magnetic slag content in the salt bath just can reduce.Per tour is done several times as one sees fit like this in the working process, and magnetic slag can maintain muchly≤and 1.0%.If propose stainless steel box, the outer adherent slag of box is very fast dirty automatically together with salt bath, and the place of corresponding permanent magnet end face does not have or almost do not adsorb slag, and at this moment magnetic slag content＜0.2%.For guaranteeing that magnetic slag in the salt bath in the scope of 0.2-1.0%, proposes box, when the remaining magnetic slag in the outer respective magnet end of the dirty back box of salt remains thin one deck, should stop the removing of magnetic slag.

As hanger, workpiece is inhaled and is attached to outside surface the stainless steel box of dress permanent magnet, and sulfurizing and absorption magnetic slag just can carry out simultaneously.Sulfurizing finishes the back and proposes box, pushes workpiece, and water washes down absorption slag and sticking salt again.Do like this and kill two birds with one stone.The magnetic slag of the outer absorption of the box of respective magnet end face is less, or after unloading workpiece, when the outer slag of box is easy to water and washes away, only pushes workpiece, does not wash outside the box, to guarantee the magnetic slag in the salt bath enough content is arranged: 〉=0.2%.

3, the non magnetic slag that obviously the visible particle is bigger in salt bath more for a long time, activity begins to reduce.Should in time in salt bath, add new salt,, make the slag granular so that non magnetic slag is changed into magnetic slag.New salt addition adds the 0.35-0.7 kilogram for whenever oozing 1 square metre of area, and per tour is added once.New salt comprises the new salt of using when beginning to prepare whole groove salt.Can guarantee that so non magnetic slag long term maintenance in the salt bath is≤1.0%.

After 2,3 two work are accomplished, the total slag content in the salt bath can guarantee≤2.0%.

4, the said recovery salt of the present invention is: the adhesive tape salt that workpiece is regained after the sulfurizing, the salt and the active bad aging salt that sweep away during towards magnetic slag, mix, water melt into saturated solution left standstill more than 24 hours, allow insolubles fully precipitate, draw out top clean solution then, contain in Stainless Steel Kettle (groove), be heated to 150-180 ℃, constant temperature 10-24 hour, evaporation water purification branch, cool to room temperature becomes the crystallization crystal again, and inclining, it is stand-by to be placed on the close drying place.

The present invention is that the highly active method of above-mentioned permanent maintenance is applicable to: the salt bath composition is 60-75%KSCN+40-25%NaSCN; Sulfurizing technology is: workpiece is made anode, and the salt pot shell is made negative electrode, volts DS 1.5-3V, current density 0.3～0.5A/dm ², salt temperature 180-200 ℃, 5-25 minute sulfurizing time.

For example practical:

Salt bath fundamental component: 75%KSCN+25%NaSCN.Trough capacity: about 65 kilograms of salt.Salt bath proportioning during beginning: 10% new salt+90% reclaims salt.Every stove batch (promptly at every turn wanting the surface-area of sulfurizing workpiece): about 0.5 square metre.Sulfurizing technology: volts DS 2-2.6V, galvanic current 16-18A (0.32-0.36A/dm ²), temperature 190-195 ℃, time 10-13 minute.The stainless steel box of interior dress 500-900 Gauss permanent magnet, the hanger that not only is used to draw magnetic slag but also regards clamping workpiece.Sulfurizing finishes, and proposes box, unloads workpiece, and water washes down the slag and the adherent salt of the outer absorption of box.Whenever oozing a stove all does like this.If the magnetic slag that the outer absorption of box is difficult for flowing away is less, or water is when being easy to rinse out, and only unloads that workpiece is non-flushing to be washed, to guarantee magnetic slag content 〉=0.2% in the salt bath.The particle of slag obviously becomes big in salt bath, shows that non magnetic slag is higher, should reduce its concentration: add new salt, each class adds the 0.4-0.45 kilogram by whenever oozing 1 square metre of area.Heat surplus the sulfurizing 500, promptly behind 250 square metres of the sulfurizing areas, dregginess remains in the salt bath: total quantity of slag＜1.5%, magnetic slag 0.3-0.8%, non magnetic slag＜0.8%, salt bath is active good, does not have any aging sign.

Claims

1, a kind of salt-bath low-temp electrolysis sulfurizing method of steel-iron components, it is characterized in that in the sulfurizing process stainless steel box of inside being filled 500～1200 Gauss's permanent magnets places 170～200 ℃ salt bath to stop 10～45 minutes, magnetic slag in the salt bath can be attracted to outside the box, magnetic slag and adherent salt that the box water washes away the outer absorption of box are proposed then, thresh several times, per tour is done several times as one sees fit like this; When the box outside surface that proposes after salt bath is dirty, the remaining magnetic slag in corresponding permanent magnet end should stop the removing of magnetic slag when remaining than book one deck; The non magnetic slag that obviously the visible particle is bigger in the salt bath adds once new salt more for a long time in salt bath simultaneously, and non magnetic slag is changed into magnetic slag, and addition is to comprise when groove salt is put in order in preparation used 6～15% new salt, whenever oozes 1m ²Surface-area adds 0.35～0.7kg; Slag content in the salt bath can remain on muchly like this: magnetic slag 0.2～1.0%, non magnetic slag≤1.0%, total quantity of slag≤2.0%.

2, press the method for claim 1, the stainless steel box that it is characterized in that adorning permanent magnet also can be done the anchor clamps of clamping workpiece, workpiece is inhaled and is attached to outside surface, sulfurizing with draw magnetic slag and combine and carry out, sulfurizing finishes back proposition box and pushes workpiece, and water washes down outer slag that adsorbs of box and sticking salt, and is less as if the outer magnetic slag that adsorbs of the box of respective magnet end face, or push the outer slag of workpiece back box and be easy to water and wash away, only push workpiece and do not wash outside the box.

3, by the method for claim 1, when it is characterized in that beginning to prepare salt bath, new salt 6～15% reclaims salt 94～85%; The chemical ingredients of salt bath is 60～75%KSCN, 40～25%NaSCN; Reclaim salt and be meant that the salt that sweeps away when washing magnetic slag outside stainless steel box, the adhesive tape salt and the active aging salt that goes down that wash from the workpiece supernatant mix, water melt into saturated solution leaves standstill 24 hours to allow the abundant post precipitation of insolubles, draw out clean solution, contain in stainless steel tank internal heating to 150～180 ℃, constant temperature evaporation in 10～24 hours water purification part, the crystallization crystal that cool to room temperature forms.

4, by the method for claim 1, it is characterized in that the sulfurizing technology parameter is: volts DS 1.5～3V, current density 0.3～0.5A/dm ², 180～200 ℃ of salt temperatures, 5～25 minutes sulfurizing time.