CN104372284A - Preparation method of plasma sprayed TiN coating layer having relatively good hardness and toughness - Google Patents

Abstract

The invention discloses a preparation method of a TiN coating layer, wherein the method comprises the following steps: (1) preparation of a TiN agglomerated powder; (2) mold surface pretreatment; (3) spraying: spraying by a plasma spraying gun, wherein spraying parameters comprise that spraying main gas is argon gas, and the gas flow rate is 38 L.min<-1>-42 L.min<-1>; secondary gas is hydrogen gas, and the gas flow rate is 12 L.min<-1>-16 L.min<-1>; powder feeding gas is argon gas, and the spraying distance is 100-140 mm; the powder feeding rate is 40 g.min<-1>, and the spraying voltage is 41 kW-50 kW; and the spraying current is 500 A-600 A; and (4) preparation of the TiN coating layer. The TiN coating layer is prepared by adopting plasma spraying of the TiN powder, and the method can adopt the powder for direct spraying, is convenient to operate and easy to popularize, and greatly saves the cost. The TiN coating layer is obtained by adopting supersonic plasma spraying, the hardness is relatively high and can reach 1210 HV0.1, the high hardness can improve the wear resistance of the coating layer, the fracture toughness of the coating layer is relatively large, the fracture mechanical properties in the coating layer can be improved, and the fatigue life of the coating layer is prolonged.

Description

The preparation method of a kind of hardness and toughness good plasma spraying TiN coating

Technical field

The present invention relates to material technology research field, be specifically related to a kind of plasma-coated preparation method.

Background technology

TiN coating has low frictional coefficient and high hardness, and good erosion resistance is widely used as decorative coveringn, wear-resistant coating, corrosion-resistant finishes.At present, many investigators by reaction thermal spraying, chemical vapour deposition (CVD), physical vapor deposition (PVD), the lonely plating of electricity, etc. technology prepared TiN coating, and the deposition process to coating, microstructure and performance are studied.The TiN coat-thickness adopting the technology such as CVD, PVD to prepare is thinner, reduces the mechanical property of coating; And utilize thermospray reaction technology can prepare thicker TiN coating, but containing more hole in coating, fragility is comparatively large, and coating quality is wayward.Adopt plasma spray technology direct spraying TiN powder can prepare thicker coating at short notice, be oxidized at spraying process TiN simultaneously, produce the oxide compound phase of Ti, the toughness of coating can be improved.

Plasma spraying technology is widely used in preparing metal, pottery and compound coating to resist wearing and tearing, corrosion and high temperature.In spraying process, the microdefects such as easy generation oxide compound and hole, this be due to melt granules fusing and flight and with matrix surface contact process in there occurs chemical reaction with surrounding medium, spray material is made to occur oxidation, but also scatter and disappear due to the bounce-back of piling superimposition partial particulate successively of melt granules, inevitably there is hole between particles.The microdefects such as coating inner oxide content and porosity pass judgment on the major criterion of coating quality, there are the control of oxide compound in scholar's microstructure of plasma sprayed process and the impact of porosity on coating performance to be studied, significantly can improve the microstructure and properties of coating by controlling suitable processing parameter.Easily decompose oxidation under TiN high temperature, activity comparatively large, in Plasma Spraying Process Using, react with other medium the oxide compound generating Ti, the oxide compound of Ti compare TiN phase hardness and intensity lower, TiN coating inner oxide content directly affects coating performance.Fracture toughness property is the ability of material repels rupture failure, the measurement of pressing in method to coating failure toughness is adopted to be used widely, coating hardness and fracture toughness property are coating opposing crackle propagation and the leading indicator that fracture occurs, and directly affects military service performance and the life-span of coating.

At present, many investigators by reaction thermal spraying, chemical vapour deposition (CVD), physical vapor deposition (PVD), electric arc plating, etc. technology prepared TiN coating, and the deposition process to coating, microstructure and performance are studied.The TiN coat-thickness adopting the technology such as CVD, PVD to prepare is thinner, reduces the mechanical property of coating; And utilize thermospray reaction technology can prepare thicker TiN coating, but containing more hole in coating, fragility is comparatively large, and coating quality is wayward.And adopt plasma direct spraying TiN powder, namely can ensure the thickness of coating, meanwhile, in TiN coating, the oxide compound of Ti can improve the toughness of coating mutually, thus obtains toughness and hardness TiN coating all preferably.

Summary of the invention

In order to solve the problem, the object of this invention is to provide a kind of preparation method of TiN coating.

In order to realize object of the present invention, the invention provides a kind of method preparing TiN coating, it comprises the steps:

(1) prepare TiN reunion powder: it is Ti-72% and N-28% that this powder comprises atomic fraction, it forms particle diameter after reuniting is 40 ~ 80 μm of spherical agglomeration bodies;

(2) die surface pre-treatment;

(3) spray: utilize plasma gun to spray, spray parameters is, spraying main gas is argon gas, and gas flow is 38Lmin ^-1-42Lmin ^-1; Secondary gas is hydrogen gas flow is 12Lmin ^-1-16Lmin ^-1; Powder feeding gas is argon gas, and spray distance is 100-140mm; Powder sending quantity is 40gmin ^-1, spray voltage is 41KW-50KW; Spraying current is 500A-600A;

(4) obtained TiN coating: this coating three strongest ones peak is TiN phase mutually, also there is part TiO, TiO ₂and Ti ₃o oxide compound phase.

Preferably, prepare step (1) in the method for TiN coating to be specially:

(1-1) TiN powder stock is atomized, and powder diameter is 1-5 μm;

(1-2) carry out batch mixing to the TiN powder after atomization and binding agent to join in agglomeration devices and reunite, and drying is carried out, granulation formation to the powder after reuniting;

(1-3) powder after reunion is passed through-200 order ~ 400 order powder sieves, the TiN reunion powder particle diameter obtained is the spherical coacervate of 40-80 micron.

More preferably, adopt polyvinyl alcohol (PVA) as binding agent, binding agent adds and is generally no more than 1% (mass ratio), and it can be used for regulating free flowing powder.

Preferably, the pre-treatment of step (2) tool die surface comprises the grinding of mould, cleaning and sandblasting.

More preferably, step (2) concrete steps are:

(2-1) first ground is carried out to die surface, make the roughness of die surface reach Ra=0.8 μm;

(2-2) then alcohol or acetone cleaning are carried out to die surface, remove the greasy dirt of die surface;

(2-3) carry out sandblasting to die surface, sand-blast material selects particle diameter to be less than the Brown Alundum of 700 μm, and sandblasting air pressure is 0.7MPa, and sandblasting angle is 45 °, and spray gun is 0.15m from die surface distance.

Preferably, step (3) concrete steps are:

(3-1) under spray parameters, utilize supersonic plasma spray gun to spray workpiece surface, scanning process adopts the scanning of " well " word, and sweep velocity is 1.25m/min;

(3-2) according to sedimentation velocity, 4 ~ 6 " well " word scanning is carried out to workpiece surface, obtain the coating that thickness is about 200 μm of thickness.

More preferably, in step (3), spray parameters is that spraying main gas is argon gas, and gas flow is 38Lmin ^-1; Secondary gas is hydrogen gas flow is 16Lmin ^-1; Powder feeding gas is argon gas, and spray distance is 125mm; Powder sending quantity is 40gmin ^-1, spray voltage is 46KW; Spraying current is 540A.

Preferably, prepare step (4) in the method for TiN coating to be specially:

(4-1) TiN its melting point is about 2950 DEG C, and dusty spray TiN reunion powder melts under the high temperature of beam-plasma, and Supersonic Plasma Spraying equipment can make melting powder have high flight velocity, can form finer and close coating;

(4-2) dusty spray is owing to depositing on matrix, and fusing particle, in flight course, there occurs reaction with ambient air, creates oxidation, generate TiO, Ti ₃o, TiO ₂oxide compound, the oxide compound of Ti compare TiN phase intensity and hardness lower, the toughness of coating can be improved.

Beneficial effect of the present invention is as follows:

The present invention directly sprays TiN powder, directly can prepare abrasion-proof ceramic coat by piece surface again, and the appearance of Ti oxide compound in coating, improves the toughness of coating.Direct spraying TiN coating can avoid fragility that traditional employing reactive spray TiN layer is larger and complex process, needs more human and material resources.

The present invention adopts supersonic spray coating TiN coating, and coating is finer and close, has a small amount of space, is combined well with matrix, thickness about 200 μm, adopts pressing in method to measure coating failure toughness to be

The present invention adopts the TiN coating of plasma spraying TiN powder preparation, and the method can adopt powder direct spraying, easy to operate, is easy to promote, and has saved cost greatly.

The present invention adopts Supersonic Plasma Spraying TiN coating, and hardness is higher, can reach 1210HV _0.1, high hardness can improve the wear resistance of coating, and the fracture toughness property of coating is comparatively large, can improve fracture mechanical property in coating, extend the fatigue lifetime of coating.

Accompanying drawing explanation

The TiN coating that Fig. 1 embodiment of the present invention 1 is obtained;

Fig. 2 spray power is to the effect tendency figure of porosity;

Fig. 3 spray distance is on the impact of oxide content;

The XRD test result of Fig. 4 coating;

The SEM of Fig. 5 coating scans pattern;

Fig. 6 coating hardness test result;

Fig. 7 fracture toughness property test vickers indentation;

Fig. 8 different porosities is on the impact of coating hardness;

The different oxide content of Fig. 9 is on the impact of coating failure toughness.

Embodiment

The present invention is introduced in detail below in conjunction with accompanying drawing and embodiment thereof.But protection scope of the present invention is not limited to following instance, the full content in claims should be comprised.

The conventional instrument used in following examples, fermentor tank model used is BIOSTAR Bplus, Germany.

The preparation of embodiment 1 coating

The preparation process of coating is divided into preparation TiN reunion powder, die surface pre-treatment, spray parameters optimization, spraying four-stage, and four-stage step is as follows:

(1) TiN reunion powder is prepared;

(1-1) be that the TiN powder of 1-5 μm is atomized for raw material with powder diameter;

(1-2) carry out batch mixing to the TiN powder after atomization and binding agent to join in agglomeration devices and reunite, and drying is carried out to the powder after reuniting, cooling;

(1-3) powder after reunion is passed through-200 order ~ 400 order powder sieves, the TiN reunion powder particle diameter obtained is the spherical coacervate of micron of 40-80 micron.

It is Ti-72% and N-28% that this powder comprises atomic fraction, and it forms particle diameter after reuniting is 40 ~ 80 μm of spherical agglomeration bodies.

(2) die surface pre-treatment;

(2-1) first ground is carried out to die surface, make the roughness of die surface reach Ra=0.8 μm;

(2-2) then alcohol or acetone cleaning are carried out to die surface, remove the greasy dirt of die surface;

(2-3) carry out sandblasting to die surface, sand-blast material selects particle diameter to be less than the Brown Alundum of 700 μm, and sandblasting air pressure is 0.7MPa, and sandblasting angle is 45 °, and spray gun is 0.15m from die surface distance.

(3) spray

(3-1) spraying equipment adopts supersonic plasma spray gun, and spray parameters is, spraying main gas is argon gas, and gas flow is 38Lmin ^-1; Secondary gas is hydrogen gas flow is 16Lmin ^-1; Powder feeding gas is argon gas, and spray distance is 125mm; Powder sending quantity is 40gmin ^-1, spray voltage is 46KW; Spraying current is 540A;

(3-2) under spray parameters, utilize supersonic plasma spray gun to spray workpiece surface, scanning process adopts the scanning of " well " word, and sweep velocity is 1.25m/min;

(3-3) according to sedimentation velocity, 4 ~ 6 " well " word scanning is carried out to workpiece surface, obtain the coating that thickness is about 200 μm of thickness;

(4) obtained TiN coating

(4-1) TiN its melting point is about 2950 DEG C, and dusty spray TiN reunion powder melts under the high temperature of beam-plasma, and Supersonic Plasma Spraying equipment can make melting powder have high flight velocity, can form finer and close coating;

(4-2) dusty spray is owing to depositing on matrix, and fusing particle, in flight course, there occurs reaction with ambient air, creates oxidation, generate TiO, Ti ₃o, TiO ₂oxide compound, the oxide compound of Ti compare TiN phase intensity and hardness lower, the toughness of coating can be improved.

As shown in Figure 1, coating is finer and close, has a small amount of space, is combined well with matrix, thickness about 200 μm for obtained TiN coating, adopts pressing in method to measure coating failure toughness to be

The impact of embodiment 2 spray parameters

Spray power in spray parameters, spray distance is the leading indicator affecting coating, have employed 10 kinds of different technical parameters and is optimized coating, and specifically as shown in Table 1 and Table 2, the judgment criteria of optimizing index is hardness and fracture toughness property.

Spray parameters under the different spray power of table 1

Spray parameters under the different spray distance of table 2

By changing ST1-ST5 five kinds of processing parameters, the result of different spray power to hardness is as follows, under ST4 processing parameter, when spray power is 46KW, coating hardness is the highest, is 1402HV0.1, ST5, ST3, ST1, under ST2 technique, the hardness of coating reduces successively, is respectively 1248HV0.1,1096HV0.1,1012HV0.1,985HV0.1.

By changing ST6-ST10 five kinds of processing parameters, under best spray power, different spray distance is the major cause causing oxide content in coating different, thus result in the fracture toughness property difference of coating.Under ST8 processing parameter, when the oxide content of coating is about 16%, the fracture toughness property of coating is maximum, for under ST10, ST7, ST9, ST6 processing parameter, the fracture toughness property of coating reduces successively, is respectively

By changing the spray parameters of coating, the change of spray power has a direct impact coating mesoporosity rate, affects result as indicated at 3:

The size of coating porosity under the different spray power of table 3

The reduction of spray power, there is the trend of first increases and then decreases in coating internal porosity, when spray power is 46KW, coating internal porosity is minimum, specifically as shown in Figure 2.

Embodiment 3 spray distance is on the impact of oxide content

Utilize three kinds of parameter detecting spray distances on the impact of oxide content, specifically as shown in table 4.

Table 4 spray distance affects coating FDS result under three kinds of parameters to oxide content

The increase of spray distance, there is the trend first reducing to increase afterwards in coating inner oxide, when spray distance is 125mm, coating inner oxide content is minimum, specifically see Fig. 3.

The performance of embodiment 4 embodiment 1 floating coat

In order to measure phase composition and phase structure in coating, the coating adopting BRUKER company D8 type X-ray analysis diffractometer (XRD) obtained to embodiment 1 carries out phase composition analysis, diffraction target is Cu target, and wavelength is 0.154056nm, test result as shown in Figure 4 shown in.

Figure 4 shows that TiN coating XRD figure is composed, through contrast PDF card, the three strongest ones peak in figure is TiN phase mutually, and TiN phase has strong (200) orientation, there is part TiO, TiO ₂and Ti ₃o oxide compound phase, this is owing to there occurs oxidation under TiN high temperature in Plasma Spraying Process Using, generates the oxide compound of Ti.TiO and Ti in coating ₃the existence of O metastable phase is due to the insufficient formation of deposits of the oxidation of TiN in Plasma Spraying Process Using.The intensity at TiN phase three strongest ones peak, much larger than the intensity of oxide compound phase, illustrates in coating and is mainly TiN phase.

In order to determine the distribution situation of each element in coating, the EDS energy spectrometer adopting Nova NanoSEM450 type scanning electronic microscope to adopt has carried out ultimate analysis to TiN coating, specifically as shown in Fig. 5 and table 5, with determine in coating each mutually between in conjunction with situation.

Table 5 coating EDS result

As can be seen from cross-sectional scans photo Fig. 5, in coating, there is light and shade phase layered distribution, have a small amount of hole in laminate structure inside and laminate structure junction.Ti element distribution uniform in whole cross section can be found out from element Surface scan distribution plan, N element and O element are regional allocations, and it is Ti and N that composition is rich in the A district that in SEM picture, color is darker, and a small amount of O, on the contrary, it is Ti, O and a small amount of N that composition is rich in the B district that color is brighter.In conjunction with XRD result, can analyze A district main component is TiN phase, and the main component in B district is Ti oxide compound phase and a small amount of TiN phase.The difference of A and B color, may be mainly oxide compound phase content difference caused by.

Adopt HVS-1000 type digital readout Vicker hardness tester testing coating microhardness, microhardness loaded load is 100g, loading time 15S, and number of checkpoints is 10 points, and the average hardness of coating reaches 1210HV _0.1, can find out that coating has higher hardness, specifically as shown in Figure 6.

Adopt HVS-1000 type digital readout Vicker hardness tester to extrude impression, as shown in Fig. 7 and table 6, and utilize the following formulae discovery of the pressing in method fracture toughness property of coating:

$\mathrm{Hv}=\frac{0.4636P}{a^2}---\left(1\right)$

$K_{\mathrm{IC}}=\frac{0.016{(E/H)}^{\frac{1}{2}}P}{c^{\frac{3}{2}}}---\left(2\right)$

In formula (1): a is the half of diagonal lines impression length; P is loaded load; In formula (2): E is Young's modulus; C is the length from impression center to crackle limit radial cracking.

Table 6 coating failure toughness K _iCcalculating parameter

In coating, spray parameters is on the impact of porosity and oxide compound, also has impact to hardness and fracture toughness property

Coating internal porosity to the effect tendency figure of hardness as shown in Figure 8, can be found out, under three kinds of techniques, increase with coating internal porosity, coating hardness is in obviously reducing trend.During porosity, the hardness of coating is the highest, is 1402HV0.1.

Coating inner oxide to the effect tendency of fracture toughness property, as shown in Figure 9.Can finding out, increasing the fracture toughness property of coating with oxide content in first increasing the trend reduced afterwards, when oxide content is about 16%, the Fracture Toughness of coating is maximum, for

The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the technology of the present invention principle; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (8)

1. prepare a method for TiN coating, it comprises the steps:

(1) prepare TiN reunion powder: it is Ti-72% and N-28% that this powder comprises atomic fraction, it forms particle diameter after reuniting is 40 ~ 80 μm of spherical agglomeration bodies;

(2) die surface pre-treatment;

(3) spray: utilize plasma gun to spray, spray parameters is, spraying main gas is argon gas, and gas flow is 38Lmin ^-1-42Lmin ^-1; Secondary gas is hydrogen gas flow is 12Lmin ^-1-16Lmin ^-1; Powder feeding gas is argon gas, and spray distance is 100-140mm; Powder sending quantity is 40gmin ^-1, spray voltage is 41KW-50KW; Spraying current is 500A-600A;

(4) obtained TiN coating: this coating three strongest ones peak is TiN phase mutually, also there is part TiO, TiO ₂and Ti ₃o oxide compound phase.

2. the method for claim 1, is characterized in that, step (1) concrete steps are:

(1-1) TiN powder stock is atomized;

(1-2) carry out batch mixing to the TiN powder after atomization and binding agent to join in agglomeration devices and reunite, and drying is carried out to the powder after reuniting, cooling;

(1-3) powder after reunion is passed through-200 order ~ 400 order powder sieves, the TiN reunion powder particle diameter obtained is the spherical coacervate of 40-80 micron.

3. method as claimed in claim 2, it is characterized in that, described binding agent is polyvinyl alcohol, and binding agent adds and is no more than 1% of TiN powder quality.

4. the method for claim 1, is characterized in that, the pre-treatment of step (2) tool die surface comprises the grinding of mould, cleaning and sandblasting.

5. method as claimed in claim 4, it is characterized in that, step (2) concrete steps are:

(2-1) first ground is carried out to die surface, make the roughness of die surface reach Ra=0.8 μm;

(2-2) then alcohol or acetone cleaning are carried out to die surface, remove the greasy dirt of die surface;

(2-3) carry out sandblasting to die surface, sand-blast material selects particle diameter to be less than the Brown Alundum of 700 μm, and sandblasting air pressure is 0.7MPa, and sandblasting angle is 45 °, and spray gun is 0.15m from die surface distance.

6. the method for claim 1, is characterized in that, step (3) concrete steps are:

(3-1) under spray parameters, utilize supersonic plasma spray gun to spray workpiece surface, scanning process adopts the scanning of " well " word, and sweep velocity is 1.25m/min;

(3-2) according to sedimentation velocity, 4 ~ 6 " well " word scanning is carried out to workpiece surface, obtain the coating that thickness is about 200 μm of thickness.

7. the method for claim 1, is characterized in that, in step (3): spray parameters is, spraying main gas is argon gas, and gas flow is 38Lmin ^-1; Secondary gas is hydrogen gas flow is 16Lmin ^-1; Powder feeding gas is argon gas, and spray distance is 125mm; Powder sending quantity is 40gmin ^-1, spray voltage is 46KW; Spraying current is 540A.

8. the method for claim 1, is characterized in that, step (4) concrete steps are:

(4-1) TiN its melting point is about 2950 DEG C, and dusty spray TiN reunion powder melts under the high temperature of beam-plasma, and Supersonic Plasma Spraying equipment can make melting powder have high flight velocity, can form finer and close coating;

(4-2) dusty spray is owing to depositing on matrix, and fusing particle, in flight course, there occurs reaction with ambient air, creates oxidation, generate TiO, Ti ₃o, TiO ₂oxide compound, the oxide compound of Ti compare TiN phase intensity and hardness lower, the toughness of coating can be improved.