CN1136331C - Pulse glow discharge plasma surface metallurgical technology - Google Patents

Abstract

The present invention relates to the metallurgical technology of the plasma surface of pulse glow discharge, which belongs to the field of surface metallurgy. The metallurgical technology of the plasma surface of pulse glow discharge is characterized in that a metal element to be permeated is placed in an airtight vacuum chamber as a source electrode; a permeated workpiece is used as a negative electrode and a common positive electrode is placed; two sets of pulse direct current sources are arranged between the source electrode and the common positive electrode and between the negative electrode and the common positive electrode. Under certain conditions, the problems of small holes, narrow grooves, deep holes and diffusion metallizing are solved, the surface alloy content of the diffusion metallizing is prompted to increase, the permeated layer thickness is increased, crystal grains are refined, the source electrode sputtering quantity is increased and the interaction of parameters is small to be independently adjusted; the present invention has the advantages of good arc extinction effect, high temperature rise rate, time saving and energy source saving.

Description

Pulse glow discharge plasma surface metallurgical technology

Pulse glow discharge plasma surface metallurgical technology of the present invention belongs to the category of surface metallurgic, particularly is the new process that a kind of material surface carries out modification.

At present, the performance requriements to material in the industry is more and more higher, and the inefficacy of material is usually concentrated from the teeth outwards, therefore, to replace expensive whole alloy, carry out material surface modifying at the cheap high performance material of material surface plating, have very high practical value.

Now laid-open U.S. Patents double glow plasma surface alloying technique (patent No. is 4520268) is that source electrode, anode and negative electrode are set in a sealed vessel, an external respectively tunable voltage dc power supply is controlled between source electrode and anode and negative electrode and the anode, utilizing not, the equi-potential hollow cathode effect infiltrates alloying element at material surface, disclosed Chinese patent CN87104358 is applied to cutting tools with double glow plasma surface alloying technique in addition, serrated surface is carried out modification, form the alloy layer of similar rapid steel composition.

Utilizing double glow plasma surface alloying technique to carry out surface alloying and realizing in the process of industrialization, metallic cementation for aperture, narrow groove, deep hole is still a difficult problem, three kinds have often been gone wrong: can not ooze, aura is concentrated and arc discharge, for example when the saw blade that is stacked is irregular (this is difficult to be avoided in actual production), all saw blade depth of penetration that falls in often do not reach requirement and become waste product.

Pulse glow discharge plasma surface metallurgical technology purpose of the present invention is to utilize the concentration of energy that is had in the pulse glow discharge process, intermittence is arranged, characteristics such as frequency adjustable, be intended to solve the problem that exists in the above-mentioned double-layer metallic glow ion cementation, thereby propose a kind of technical scheme that replaces the direct current glow discharge metallic cementation with pulse glow discharge.

Pulse glow discharge plasma surface metallurgical technology of the present invention is to desire the metallic cementation element as source electrode indoor setting of enclosed vacuum, oozed workpiece as negative electrode, and placement public anode, configuration two the cover pulse powers or one of them are set to the pulse power between source electrode and anode and negative electrode and the anode, another still is a tunable voltage dc power supply, and wherein the pulse power is the orthogonal pulse dc power for the successive current waveform.

During glow discharge, the cathode fall section length $d_k=\frac{a}{\sqrt{j}}+\frac{b}{p},$ J-current density in the formula, p-air pressure, a, b-constant are added negative glow and are called the cathodic discharge length d.Realize that the essential condition of carrying out metallic cementation in aperture and the narrow groove smoothly is:

With Because the pulse glow discharge outage repeats to guarantee do not beating arc than realizing metallic cementation under the high atmospheric pressure, impel workpiece to have big strength of current by regulating peak point current and duty specific energy, and in normal metallic cementation temperature range, work, thereby reduced d and d _kValue realizes metallic cementation in the seam of hole.Feed shielding gas or reactant gases, air pressure range 1.33～2000Pa, peak point current 0～200A, dutycycle 0.05～0.95, frequency 0.02～200KHz, 800～1200 ℃ of workpiece metallic cementation temperature during work.

Among the present invention, being oozed workpiece is pure iron, carbon steel, steel alloy, stainless steel, high temperature steel, nickel-base alloy, the multiple metallic substance of titanium base alloy and pottery etc.The alloying element of forming source electrode refers to W, Mo, V, Nb, Ta, Ni, Ti, Co, Cr Cu etc. and their combination mutually arbitrarily thereof, source electrode can be made different shape as brush shape, column, lath-shaped etc. and workpiece parallel opposed according to workpiece different shapes size, distance between source electrode and the workpiece is more than the 10mm, the best metallic cementation condition and range of the present invention air pressure 30～100Pa, dutycycle 0.45～0.9, frequency 500～2500Hz, 1000～1200 ℃ of temperature.

Pulse metallic glow ion cementation of the present invention is compared with the tunable voltage dc power supply metallic glow ion cementation, has the obvious effect that improves the metallic cementation degree of depth in the seam of hole, can make the seam interior metallic cementation degree of depth in hole increase to original 1.6～3.4 times.In addition, find that also metallic cementation surface alloy content improves, alloying layer thickness increases, and crystal grain is tiny, improves outstanding effects such as source electrode sputter amount, under same experimental conditions, adopt the pulse glow discharge metallic cementation, surface alloy content is 1.5～3 times of tunable voltage dc power supply metallic cementation, and alloying layer thickness is 1.2～2.4 times, source electrode sputter amount is 2.5～5 times, and the grain-size reduced radius is original 30～60%.Can improve the metallic cementation quality in a word, and it is less to influence each other between the parameter comprehensively, can regulates independently of one another, arc quenching effect is good, and heat-up rate is fast, saves time and the energy.

The specific embodiment of the invention 1: the external impressed current pulse power between workpiece and anode, external tunable voltage dc power supply between source electrode and the anode, workpiece is 20 steel, source electrode is pure W silk, be evacuated to final vacuum 2Pa, feed argon gas to operating air pressure 45Pa, connect power supply and make working parameter dutycycle 0.9, frequency 2500Hz, peak point current 10A, insulation 2h, the metallic cementation degree of depth is 2.5mm in the Φ 0.6mm hole after testing, surface alloy content 8.42wt%, alloying layer thickness 150 μ m, source electrode sputter amount 2.03g/h.

The embodiment of the invention 2: under the experiment condition of embodiment 1, choose working parameter air pressure 60Pa, dutycycle 0.1, frequency 1000Hz, peak point current 50A, insulation 2h, after testing, metallic cementation degree of depth 2.12mm in the Φ 0.6mm hole, surface alloy content 6.38wt%, alloying layer thickness 126 μ m, source electrode sputter amount 1.18g/h.

The embodiment of the invention 3, under the experiment condition identical, choose working parameter, air pressure 150Pa with embodiment 1, dutycycle 0.45, frequency 10KHz, peak point current 30A, insulation 2h, metallic cementation degree of depth 2.42mm in the Φ 0.6mm hole after testing, surface alloy content 4.28wt%, alloying layer thickness 101 μ m, source electrode sputter amount 0.9g/h.

The embodiment of the invention 4, source electrode is W, the Mo source, weight percent W: Mo=6: 4, workpiece is 20Cr, adopts and obtains the result with embodiment 1 identical condition: metallic cementation degree of depth 2.33mm in the Φ 0.6mm hole, surface alloy content W is 4.78wt%, Mo is 2.69wt%, alloying layer thickness 138 μ m, source electrode sputter amount 1.98g/h.

Claims (4)

1; a kind of pulse glow discharge plasma surface metallic cementation method; be to desire the metallic cementation element as source electrode in the indoor placement of enclosed vacuum; oozed work as negative electrode; and placement public anode; it is characterized in that between source electrode and anode and negative electrode and the anode; configuration two is overlapped the pulse powers or is disposed a cover pulse power and a cover tunable voltage dc power supply; wherein the pulse power is the orthogonal pulse dc power for the successive current waveform; feed shielding gas or reactant gases during work; air pressure 1.33Pa～2000Pa; peak point current 0～200A; dutycycle 0.05～0.95; frequency 0.02～200KHz; workpiece metallic cementation temperature is 800～1200 ℃, its cathode fall section length $d_k=\frac{a}{\sqrt{j}}+\frac{b}{p},$ J-current density in the formula, p-air pressure, a, b-constant, cathodic discharge length is d, realizes that the condition of carrying out metallic cementation in aperture and the narrow groove smoothly is: With

2,, it is characterized in that described best metallic cementation condition and range is: air pressure 30～100Pa, dutycycle 0.45～0.9, frequency 500～2500Hz, 1000～1200 ℃ of temperature according to the described pulse glow discharge plasma surface metallic cementation of claim 1 method.

3, according to the described pulse glow discharge plasma surface metallic cementation of claim 1 method, it is characterized in that described desire metallic cementation element is meant that a kind of metal or the mutual arbitrarily of them that are selected among W, Mo, V, Nb, Ta, Ni, Ti, Co, Cr and the Cu make up, being oozed workpiece is metallic substance or the pottery that is selected from pure iron, carbon steel, steel alloy, stainless steel, high temperature steel, nickel-base alloy or titanium base alloy.

4, according to the described pulse glow discharge plasma surface metallic cementation of claim 1 method, it is characterized in that described source electrode can be made according to workpiece different shapes size comprises the different shape of brushing shape, column or lath-shaped, and with the workpiece parallel opposed, the distance between source electrode and the workpiece is more than the 10mm.