CN102191447A - Tungsten carbide cobalt-copper-molybdenum disulfide self-lubricating wear-resistant coating and preparation method thereof - Google Patents

Abstract

The invention discloses a tungsten carbide cobalt-copper-molybdenum disulfide self-lubricating wear-resistant coating and a preparation method thereof. The preparation method is characterized by comprising the following steps of: preparing tungsten carbide cobalt-copper-molybdenum disulfide composite powder by taking tungsten carbide cobalt, copper and molybdenum disulfide as raw materials and by a sintering crushing method; and obtaining a tungsten carbide cobalt-copper-molybdenum disulfide composite coating by an atmospheric plasma spraying method. In the composite coating, the ratio of tungsten carbide cobalt to copper to molybdenum disulfide is equal to (70-90):(6-18):balance; and the thickness is 200 to 400mu m. Compared with the traditional tungsten carbide cobalt coating, the tungsten carbide cobalt-copper-molybdenum disulfide self-lubricating wear-resistant coating has the advantages that: the friction coefficient and the wear rate of the tungsten carbide cobalt-copper-molybdenum disulfide composite coating are remarkably reduced; and the tungsten carbide cobalt-copper-molybdenum disulfide composite coating is an excellent self-lubricating wear-resistant coating.

Description

A kind of WC-Co-copper-molybdenumdisulphide self-lubricating wear-resistant coating and preparation method thereof

Technical field

The present invention relates to a kind of WC-Co-copper-molybdenumdisulphide self-lubricating wear-resistant coating and preparation method thereof.Belong to the protective material technical field.

Background technology

The development of machinofacture and sophisticated technology and the greatest limit that performance reached of material are closely bound up, but along with improving constantly of working stress that material bore and working temperature, often make material before not reaching operating limit just owing to wearing and tearing cause losing efficacy.In the U.S., 1985 because the estimated amount of damage that wearing and tearing cause reaches 20,000,000,000 dollars.[Budinski K.G., Surface Engineering for Wear Resistance.PrenticeHall.N.J.USA.1988.] estimates to reach 2,000 hundred million dollars if wearing and tearing and the loss that corrosion causes are in the same place.[Bernecki T.F..Ceramic Industry.1989,10:39.] in Germany, brainstrust estimates annual because the loss that wearing and tearing and corrosion cause accounts for 5% of GSP greatly.[Lugscheider E., Proc.of the Nat.Thermal Spray Conf.Florida.USA.1987:105.] according to German professor's Vogelpohl prediction, 1/3 to 1/2 of the produced worldwide energy is lost in the frictional wear, [Fuller D D.Theory andPractice of Lubrication Engineer.John Wiley﹠amp; Sons, 1986.] Britain professor H.P.Jost points out, 30%～40% of the world consumption energy consumes in frictional wear.[west wind. the reasonable lubrication technical manual. petroleum industry press, 1993:5.] therefore explore minimizing and prevent that wearing and tearing, corroding method and technology have important social meaning and economic benefit.

Wolfram varbide (WC) has the fusing point height, the hardness height, and particularly its hot hardness is the highest, the characteristics of typical stupalith such as stable chemical performance.And cobalt (Co) melt is best to the wettability of wolfram varbide, is the great attention that the preparation of the metal-ceramic compound coating of representative is subjected to investigators with WC-Co (WC-Co).The technology of preparing of WC-Co coating has oxyacetylene torch spraying, plasma spraying and detonation flame spraying etc.Plasma spraying is to utilize plasma flame to come the heat fused dusty spray to make it to form coating.Dusty spray is written into plasma flame flow by powder feeding gas, is fusing or semi-molten state very soon, and sprays at a high speed in the clean piece surface generation viscous deformation through alligatoring, sticks to piece surface.Rely on viscous deformation and mutual hook knot between each molten drop, thereby obtain in conjunction with good stratiform dense coating.Therefore, often adopt plasma spraying to prepare the WC-Co coating.

But the same in other wear-resistant coatings, WC-Co coating hardness height can produce serious frictional wear to friction pair, has increased abrasion loss indirectly, and therefore, the wear rate that reduces the WC-Co coating becomes the research focus.Molybdenumdisulphide (MoS ₂) be most widely used solid lubricant, be known as lubricated king.MoS ₂Belong to hexagonal system flakey crystal, be laminate structure, Mo atom and S atomic binding forces are strong, and a little less than the power that mutually combines between the S atom.So MoS ₂Produce a shearing force plane between the molecular layer, when being subjected to shearing stress between the molecule, be easy to produce fracture, form slip plane along molecular layer.Metallic copper has good thermal conductivity, toughness, ductility and plasticity-, and fusing point higher (1085 ℃) under anoxic or air conditions, does not react oxidation products Cu with dilute sulphuric acid or organic acid ₂O has certain lubrication.In addition, the copper raw material wide material sources, cheap.Given this, the present invention's expectation is by adding MoS simultaneously in WC-Co ₂With the Cu solid lubricant, reduce the frictional coefficient and the wear rate of coating.

So far, WC-Co-copper-molybdenumdisulphide self-lubricating wear-resistant coating and adopt atmospheric plasma spraying technology to prepare this type of compound coating and do not appear in the newspapers as yet.

Summary of the invention

The object of the present invention is to provide a kind of WC-Co-copper-molybdenumdisulphide self-lubricating wear-resistant coating and preparation method thereof.

Preparation method of the present invention comprises the steps:

(1) commercially available WC-Co (WC-Co) powder, copper powder and molybdenum disulphide powder are carried out ball milling in anhydrous ethanol medium and mix, the control rotational speed of ball-mill is 100～150r/min, and mixing time is 24～48 hours.

The mean particle size of described wolfram varbide cobalt powder is 15～45 μ m, and WC grain is of a size of 200～800nm, and Co content is 10～14wt.%.

The mean particle size of described copper powder is 15～50 μ m.

The mean particle size of described molybdenum disulphide powder is 1～6m.

(2) above-mentioned mixed powder is 40～80 ℃ of oven dry down, and oven dry back powder is sintering in a vacuum, and sintering temperature is 1000～1200 ℃, and constant temperature time is 1～3 hour.

(3) with the broken powder that forms of block behind the sintering, the particle diameter of described powder is not more than 75 μ m.

(4) metal base is carried out surface preparation.

Described surface preparation comprises: cleaning, oil removing, sandblast, cutting thread or annular knurl, electric plucking etc.

Described metal base comprises: A3 soft steel, stainless steel and bearing steel etc.

(5) be raw material with step (3) gained powder, adopt the air plasma spraying method to prepare coating.

Described air plasma spraying method is main gas with argon gas, and hydrogen is auxilliary gas, and is powder feeding gas with the argon gas.

The gas flow that described air plasma spraying method is controlled main gas and auxilliary gas is respectively 45～75slpm and 2～4slpm; Control powder feeding gas flow is 3～6slpm, and powder feeding rate is 12～16rpm; Control current is 350～450A in the spraying process, and voltage is 50～60V, and spray distance is 100～120mm, and control spray time and number of times make that prepared coat-thickness is 200～400 μ m.

The component that the present invention makes coating is WC-Co, copper and molybdenumdisulphide, and thickness is 200～400 μ m.

Described coating ingredients content is: WC-Co: copper: molybdenumdisulphide=(70～90): (6～18): surplus.

Described coating ingredients preferable range is: WC-Co: copper: molybdenumdisulphide=(70～75): (15～18): surplus.

Owing to the provide protection of add copper, the decarburization of wolfram varbide in Plasma Spraying Process Using reduces, and fragility reduces mutually in the compound coating, and fatigue wear disappears.While MoS ₂In compound coating, preserve better, in friction process, play solid lubricant.

WC-Co-copper-molybdenumdisulphide compound coating with the mating plate friction process in, there is abrasive dust to produce in the friction pair contact position,, between friction pair, smears and form the abrasive dust layer because abrasive dust hardness is lower, this abrasive dust layer has the solid lubrication effect, has reduced the frictional wear of compound coating.

Utilize scanning electronic microscope (SEM), energy spectrometer (EDS) and UMT multifunction friction wear tester characterize resulting sample.

Prepared coating is used successively the Al of different-grain diameter ₂O ₃Abrasive material carries out surface grinding, and is polished to surfaceness with diamond paste: Ra=0.5 μ m.Adopt UMT multifunction friction wear tester, friction-wear test is carried out in ball-dish way of contact.Testing used is 302 Stainless Steel Balls of diameter 4mm to abrading-ball, and hardness is RC39.Other experiment parameters: positive pressure 10N, line of slide speed 0.5m/s, fraction time 20 minutes, 600 meters of friction strokes.

Frictional coefficient is directly read by friction device, adopts surface profiler to measure the polishing scratch sectional area, and sectional area and polishing scratch girth multiply each other and draw wear volume, and wear rate is calculated by following formula, and frictional coefficient and wear rate value are all got the mean value of 5 repeated experiments.

$W=\frac{\mathrm{\ΔV}}{\mathrm{FL}}$

In the formula: W---wear rate; Δ V---wear volume; F---positive pressure; L---friction stroke.

Advantage of the present invention:

(1) adopt the WC-Co-copper-molybdenumdisulphide compound coating of air plasma spraying preparation and traditional WC-Co coating to compare, coating structure is even, compact structure, and crackle and voids content reduce.

(2) adopt the WC-Co-copper-molybdenumdisulphide compound coating of air plasma spraying preparation and traditional WC-Co coating to compare, the WC decarburization is less, and the fragility phase content is lower, and the fatigue wear that is caused by repeated stress is not remarkable, and MoS ₂In coating, preserve better, in friction process, play the solid lubrication effect.

(3) adopt the WC-Co-copper-molybdenumdisulphide compound coating friction and wear behavior of air plasma spraying preparation all to be significantly improved.The coating ingredients scope of frictional behaviour the best is among the present invention: WC-Co: copper: molybdenumdisulphide=(70～75): (15～18): surplus.Its frictional coefficient and wear rate can be reduced to respectively and be about 0.05 and (6.7 ± 0.4) * 10 ^-5Mm ³N ^-1m ^-1, be about 12% and 26% of traditional WC-Co coating respectively.

Description of drawings

Each Figure of description is done schematic illustration

Fig. 1 is (a) traditional WC-Co coating; (b) 90wt.%WC-Co-6wt.%Cu-4wt.%MoS ₂Coating; (c) 80wt.%WC-Co-12wt.%Cu-8wt.%MoS ₂Coating and (d) 70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂The SEM figure of coating glazed surface.The result shows, traditional WC-Co coating and 90wt.%WC-Co-6wt.%Cu-4wt.%MoS ₂Coating structure is similar, and hole and crackle content are more.80wt.%WC-Co-12wt.%Cu-8wt.%MoS ₂Coating and 70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂The coating structure densification.

Fig. 2 is (1) traditional WC-Co coating; (2) 90wt.%WC-Co-6wt.%Cu-4wt.%MoS ₂Coating; (3) 80wt.%WC-Co-12wt.%Cu-8wt.%MoS ₂Coating and (4) 70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂The change curve of the The friction coefficient fraction time of coating.The result shows, WC-Co-Cu-MoS ₂The frictional coefficient of coating all is lower than traditional WC-Co coating.

Fig. 3 is (1) traditional WC-Co coating; (2) 90wt.%WC-Co-6wt.%Cu-4wt.%MoS ₂Coating; (3) 80wt.%WC-Co-12wt.%Cu-8wt.%MoS ₂Coating and (4) 70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂The wear rate of coating relatively.The result shows, WC-Co-Cu-MoS ₂Wear rate all be lower than traditional WC-Co coating.

Fig. 4 is (a) traditional WC-Co coating; (b) 90wt.%WC-Co-6wt.%Cu-4wt.%MoS ₂Coating; (c) 80wt.%WC-Co-12wt.%Cu-8wt.%MoS ₂Coating and (d) 70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂Coating frictional experiment rear surface SEM pattern.The result shows that the wearing and tearing of traditional WC-Co coating are based on fatigue wear, and WC-Co-Cu-MoS ₂The wearing and tearing of coating are based on abrasive wear.

Embodiment

Further specify the present invention below by embodiment, but the present invention is limited to embodiment absolutely not.

Embodiment 1:

The air plasma spraying powder is 70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂Powder, the spraying base material is the A3 mild steel plate.Before the air plasma spraying, adopt the SiC sand grains that the spraying substrate surface is carried out sandblast pretreatment, after the pre-treatment, sprayed with interior employing air plasma spraying system in two hours.With argon gas is main gas, and hydrogen is auxilliary gas, and the gas flow of argon gas and hydrogen is respectively 50slpm and 3slpm; With the argon gas is powder feeding gas, and the powder feeding gas flow is 5slpm, and powder feeding rate is 14rpm; The electric current that adopts in the spraying process is 400A, and voltage is 55V, and spray distance is 100mm, sprays 25 times.Prepared coat-thickness is about 250 μ m.

70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂The frictional coefficient of coating is about 0.05, and wear rate is about (6.7 ± 0.4) * 10 ^-5Mm ³N ^-1m ^-1, and the frictional coefficient of traditional WC-Co coating is about 0.42, wear rate is about (25.7 ± 2.8) * 10 ^-5Mm ³N ^-1m ^-1The frictional coefficient of compound coating and wear rate all be improved significantly.

Embodiment 2:

The gas flow of the main gas of air plasma spraying among the embodiment 1 and auxilliary gas changed into respectively be 75slpm and 3slpm, other experiment conditions are identical.Gained 70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂The frictional coefficient of coating is about 0.07, and wear rate is about (7.3 ± 0.5) * 10 ^-5Mm ³N ^-1m ^-1, and the frictional coefficient of traditional WC-Co coating is about 0.42, wear rate is about (25.7 ± 2.8) * 10 ^-5Mm ³N ^-1m ^-1The frictional coefficient of compound coating and wear rate all be improved significantly.

Embodiment 3:

Change the electric current of air plasma spraying among the embodiment 1 into 450A, other experiment conditions are identical.Gained 70wt.%WC-Co-18wt.%Cu-12wt.%MoS ₂The frictional coefficient of coating is about 0.08, and wear rate is about (6.4 ± 0.3) * 10 ^-5Mm ³N ^-1m ^-1, and the frictional coefficient of traditional WC-Co coating is about 0.42, wear rate is about (25.7 ± 2.8) * 10 ^-5Mm ³N ^-1m ^-1The frictional coefficient of compound coating and wear rate all be improved significantly.

Embodiment 4:

Change air plasma spraying among the embodiment 1 into 75wt.%WC-Co-15wt.%Cu-10wt.%MoS with powder ₂Powder, other experiment conditions are identical.Gained 75wt.%WC-Co-15wt.%Cu-10wt.%MoS ₂The frictional coefficient of coating is about 0.06, and wear rate is about (5.8 ± 0.3) * 10 ^-5Mm ³N ^-1m ^-1, and the frictional coefficient of traditional WC-Co coating is about 0.42, wear rate is about (25.7 ± 2.8) * 10 ^-5Mm ³N ^-1m ^-1The frictional coefficient of compound coating and wear rate all be improved significantly.

Embodiment 5:

Change air plasma spraying among the embodiment 1 into 80wt.%WC-Co-12wt.%Cu-8wt.%MoS with powder ₂Powder, other experiment conditions are identical.Gained 80wt.%WC-Co-12wt.%Cu-8wt.%MoS ₂The frictional coefficient of coating is about 0.24, and wear rate is about (4.7 ± 0.2) * 10 ^-5Mm ³N ^-1m ^-1, and the frictional coefficient of traditional WC-Co coating is about 0.42, wear rate is about (25.7 ± 2.8) * 10 ^-5Mm ³N ^-1m ^-1The frictional coefficient of compound coating and wear rate all be improved significantly.

Embodiment 6:

Change air plasma spraying among the embodiment 1 into 85wt.%WC-Co-9wt.%Cu-6wt.%MoS with powder ₂Powder, other experiment conditions are identical.Gained 85wt.%WC-Co-9wt.%Cu-6wt.%MoS ₂The frictional coefficient of coating is about 0.25, and wear rate is about (8.6 ± 0.5) * 10 ^-5Mm ³N ^-1m ^-1, and the frictional coefficient of traditional WC-Co coating is about 0.42, wear rate is about (25.7 ± 2.8) * 10 ^-5Mm ³N ^-1m ^-1The frictional coefficient of compound coating and wear rate all be improved significantly.

Embodiment 7:

Change air plasma spraying among the embodiment 1 into 90wt.%WC-Co-6wt.%Cu-4wt.%MoS with powder ₂Powder, other experiment conditions are identical.Gained 90wt.%WC-Co-6wt.%Cu-4wt.%MoS ₂The frictional coefficient of coating is about 0.26, and wear rate is about (13.8 ± 0.3) * 10 ^-5Mm ³N ^-1m ^-1, and the frictional coefficient of traditional WC-Co coating is about 0.42, wear rate is about (25.7 ± 2.8) * 10-5mm ³N ^-1m ^-1The frictional coefficient of compound coating and wear rate all be improved significantly.

Claims (5)

1. WC-Co-copper-molybdenumdisulphide self-lubricating wear-resistant coating is characterized in that:

Coating ingredients is WC-Co, copper and molybdenumdisulphide, and thickness is 200～400 μ m.

Coating ingredients content is: WC-Co: copper: molybdenumdisulphide=(70～90): (6～18): surplus.

The coating ingredients preferable range is: WC-Co: copper: molybdenumdisulphide=(70～75): (15～18): surplus.

2. the preparation method of WC-Co-copper according to claim 1-molybdenumdisulphide self-lubricating wear-resistant coating is characterized in that:

A, commercially available WC-Co (WC-Co) powder, copper powder and molybdenum disulphide powder are carried out ball milling mix in anhydrous ethanol medium, the control rotational speed of ball-mill is 100～150r/min, and mixing time is 24～48 hours.

B, above-mentioned mixed powder are 40～80 ℃ of oven dry down, and oven dry back powder is sintering in a vacuum, and sintering temperature is 1000～1200 ℃, and constant temperature time is 1～3 hour;

C, with the broken powder that forms of block behind the sintering, the particle diameter of described powder is not more than 75 μ m.

D, be raw material, adopt the air plasma spraying method to prepare WC-Co-copper-molybdenumdisulphide self-lubricating wear-resistant coating with step c gained powder.

3. the preparation method of WC-Co-copper according to claim 2-molybdenumdisulphide self-lubricating wear-resistant coating is characterized in that: the mean particle size of used wolfram varbide cobalt powder is 15～45 μ m, and WC grain is of a size of 200～800nm, and Co content is 10～14wt.%.The mean particle size of used copper powder is 15～50 μ m.The mean particle size of used molybdenum disulphide powder is 1～6 μ m.

4. the preparation method of WC-Co-copper according to claim 2-molybdenumdisulphide self-lubricating wear-resistant coating is characterized in that:

Described air plasma spraying method is main gas with argon gas, and hydrogen is auxilliary gas, and is powder feeding gas with the argon gas.

The gas flow that described air plasma spraying method is controlled main gas and auxilliary gas is respectively 45～75slpm and 2～4slpm; Control powder feeding gas flow is 3～6slpm, and powder feeding rate is 12～16rpm; Control current is 350～450A in the spraying process, and voltage is 50～60V, and spray distance is 100～120mm, and control spray time and number of times make that prepared coat-thickness is 200～400 μ m.

5. the preparation method of WC-Co-copper according to claim 4-molybdenumdisulphide self-lubricating wear-resistant coating is characterized in that: before the air plasma spraying metal base is carried out surface preparation.

Described surface preparation comprises: cleaning, oil removing, sandblast, cutting thread or annular knurl, electric plucking etc.

Described metal base comprises: A3 soft steel, stainless steel and bearing steel etc.

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