Quartering hammer piston and preparation method applying magnetron sputtering

Abstract

The invention provides a breaking hammer piston and a preparation method applying magnetron sputtering, and belongs to the technical field of breaking hammers. The technical problems that an existing piston is poor in friction resistance, prone to abrasion in the working process, short in service life and the like are solved. The outer surface of a piston body in the breaking hammer piston is wholly or partially provided with a strengthened coating, the strengthened coating comprises a hard layer and a bonding layer, the bonding layer is connected with the piston body, the hard layer is located on the outer side of the bonding layer, the hard layer is a DLC layer or a CrN layer or a WC layer or a WN layer or a CrNiN layer or a CrAlN layer or a CrAlNiN layer or a CrAlW layer, and the bonding layer is a Cr layer or a Ti layer or a TiN layer or a CrN layer. The preparation method comprises the steps of piston pretreatment, vacuum chamber glow cleaning, bonding layer implantation, surface hard layer deposition, post-treatment, cooling and the like. The friction-resistant rubber has the advantages of being better in friction resistance, longer in service life and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of breaker hammers, and in particular relates to a breaker hammer piston and a preparation method thereof by using magnetron sputtering. Background Art

[0002] A breaker hammer is usually installed on an excavator, loader or power station. It has the advantages of strong impact force, ease of use, good maneuverability and high efficiency. It is mainly used for crushing, demolition, excavation of hard layers and other tasks in construction.

[0003] For example, the China Patent Network discloses a new type of hydraulic nitrogen combined action breaker hammer [Authorization Announcement No.: CN201695429U], which includes a front cylinder body, a drill rod arranged in the front cylinder body, a rear cylinder body for storing nitrogen, a middle cylinder body and a piston arranged in the middle cylinder body. Two annular bosses are arranged at intervals from front to back in the middle part of the piston. When the piston descends, the high-pressure oil in the rear working chamber acts on the rear end face of the rear boss to push the piston to strike. When the piston rises, the high-pressure oil in the front working chamber acts on the front end face of the front boss to push the piston to reset. During the reciprocating motion of the piston, the boss also plays a role in the reciprocating movement of the piston. The role of guidance is that the gap between the outer peripheral surface of the boss and the inner peripheral surface of the middle cylinder body is generally a few threads, and it is difficult for the piston to maintain absolute concentricity during the reciprocating motion. Especially at the moment when the piston hits the drill rod, the piston is prone to swing to a certain extent, resulting in a decrease in the concentricity of the piston. In the subsequent process of the piston rising, the outer peripheral surface of the boss and the outer edge of the boss end face rub against the inner wall of the middle cylinder body. Over time, the boss is prone to wear and tear and the piston is strained. The entire piston needs to be replaced during maintenance. Due to the huge size of the piston of this large mechanical equipment, the maintenance cost of the breaker is huge.

[0004] Therefore, how to improve the friction resistance of the piston, prevent the piston from wearing out during operation, and extend the service life of the piston has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a breaker hammer piston with better friction resistance and longer service life, and a preparation method using magnetron sputtering.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A breaker hammer piston comprises a piston body, wherein the outer surface of the piston body is entirely or partially provided with a strengthening coating, wherein the strengthening coating comprises a hard layer and a bonding layer, wherein the bonding layer is connected to the piston body, and the hard layer is located outside the bonding layer.

[0008] The hard layer is a DLC layer, a CrN layer, a WC layer, a WN layer, a CrNiN layer, a CrAlN layer, a CrAlNiN layer, or a CrAlW layer.

[0009] The DLC layer of the hard layer is composed of an amorphous carbon-based material, wherein sp 3 The hybrid bond accounts for 40%-60%, and is doped with 1%-20% of metal or non-metal elements, the elements are Cr, Si, W, F, N, B, and their mass fraction is 0.5%-15%,

[0010] The CrN layer of the hard layer contains 45-75 at% Cr and 35-70 at% N;

[0011] The WC layer of the hard layer contains W: 32-55at%, C: 30-58at%

[0012] In the WN layer of the hard layer, W: 32-55at%, N: 30-58at%

[0013] The CrNiN layer of the hard layer contains 45-75 at % Cr, 1-15 at % Ni, and 35-70 at % N;

[0014] The CrAlN layer of the hard layer contains 20-40 at%, 15-45 at%, and 30-60 at% of Cr;

[0015] The CrAlNiN layer of the hard layer comprises 20-40 at%, 20-45 at%, 0.5-15 at%, and 30-60 at% of Cr;

[0016] The CrAlW layer of the hard layer contains 15-30 at%, 20-45 at%, 0.5-22 at%, and 23-58 at% of Cr;

[0017] The bonding layer is a Cr layer, a Ti layer, a TiN layer, or a CrN layer.

[0018] The Cr layer of the bonding layer contains 40-100 at% Cr.

[0019] Ti in the Ti layer of the bonding layer: 40-100at%,

[0020] The TiN layer of the bonding layer contains 50-60 at% Ti and 40-50 at% N;

[0021] The CrN layer of the bonding layer contains 45-60 at % Cr and 40-55 at % N.

[0022] Doping metal or non-metal elements in the DLC layer of this hard layer has the following advantages:

[0023] 1. Reduce residual stress: DLC layer usually has high sp 3 The content leads to high internal stress. Doping elements can significantly reduce the internal stress of the coating by interrupting the continuity of the carbon network or forming an amorphous structure, thereby improving the bonding strength between the coating and the substrate.

[0024] 2. Enhance hardness and wear resistance: Metal elements Cr and W combine with carbon to form hard carbides Cr7C3 or Cr3C2, WC, which can improve the hardness and wear resistance of the coating; non-metallic elements B and N can enhance the hardness and wear resistance of the coating by strengthening sp 3 bond network or form BC / NC covalent bonds to enhance the mechanical properties of the coating.

[0025] 3. Reduce the friction coefficient: Metal doping W and Cr can form self-lubricating oxide layers WO3 and Cr2O3, reducing the direct contact of the friction pair; the non-metallic element F significantly reduces the friction coefficient by forming a fluorine-rich surface layer with low shear strength (similar to the PTFE effect).

[0026] 4. Anti-adhesion and anti-bite: Doping elements Si and N can inhibit metal transfer and reduce the tendency of cold welding between the coating and the grinding material, making it suitable for high load or dry friction conditions.

[0027] The CrN layer, WC layer, WN layer, CrNiN layer, CrAlN layer, CrAlNiN layer, or CrAlW layer in the hard layer all have high hardness and wear resistance, and can enhance the mechanical properties of the coating; at the same time, the hard layer with the above ratio also has good corrosion resistance, which can increase the service life of the coating.

[0028] The above CrN coating has the advantages of good toughness, good film-substrate interface matching and good bonding strength. Both the hard layer and the bonding layer can be coated with CrN. The atomic percentage ratio of the CrN layer in the hard layer and the bonding layer is different, resulting in different performance of the CrN layer:

[0029] Cr-rich alloys form a hexagonal Cr2N or Cr+Cr2N dual-phase structure. The Cr2N phase has good toughness, and the high Cr content promotes chemical compatibility with the metal matrix and enhances interfacial bonding strength.

[0030] The high Cr content (>60at%) in the bonding layer can form a diffusion transition layer with the matrix metal Fe and Co. The mutual dissolution or reaction of Cr and matrix elements forms a Cr-Fe solid solution, which significantly improves the adhesion between the coating and the substrate; the thermal expansion coefficient of the Cr2N phase in the bonding layer is closer to that of the steel substrate, reducing the interfacial stress under thermal cycling and avoiding coating peeling.

[0031] The high nitrogen content of the hard layer promotes the formation of a dense CrN oxide film, but the Cr-rich bonding layer preferentially forms a Cr2O3 passivation film in a corrosive environment, providing dual protection for the substrate.

[0032] When the bonding layer is a Cr layer (Cr: 40-100at%), with a high Cr content (>80at%): when the high-purity Cr layer is prepared by magnetron sputtering, the residual stress is low, thereby reducing the risk of coating peeling.

[0033] Medium-low Cr content (40-80at%): Gradient transition design forms a Cr-based solid solution, alleviates the difference in thermal expansion coefficient, and improves interface bonding strength.

[0034] When the bonding layer is a Ti layer (Ti: 40-100at%), with a high Ti content (>70at%), the pure Ti layer forms a Ti-Al or Ti-Fe intermetallic compound with the substrate, and has a strong bonding force.

[0035] Medium-low Ti content (40-70at%): By introducing a small amount of N or C, the thermal conductivity is reduced and the thermal stress cracks between the substrate and the functional layer at high temperatures are reduced.

[0036] When the bonding layer is a TiN layer (Ti: 50-60at%, N: 40-50at%), it has high hardness and wear resistance: cubic phase TiN (c-TiN) has high hardness and low friction coefficient; Ti-rich or N-rich deviation (such as Ti: 60at% / N: 40at%): toughness is improved, toughness is better than pure TiN, and impact resistance is improved.

[0037] When the bonding layer is a CrN layer (Cr: 45-60at%, N: 40-55at%), the stoichiometric ratio is close to 1:1 (Cr: N≈1:1, such as 50at% Cr / 50at% N), and the cubic CrN (c-CrN) has high hardness and low residual stress; Cr-rich (Cr>55at%) or N-rich (N>50at%): the Cr-rich layer forms a Cr2N phase, reducing thermal cycle spalling; the N-rich layer (such as 55at% N): forms amorphous chromium nitride, which improves corrosion resistance.

[0038] In the above-mentioned breaker hammer piston, the strengthening coating includes a transition layer, which is arranged between the hard layer and the bonding layer, and the transition layer is a CrN layer, a WC layer, a WN layer, a CrNiN layer, a CrAlN layer, a CrAlNiN layer, a CrAlW layer, or a TiN layer.

[0039] CrN layer: Cr: 45-75at%, N: 35-70at%;

[0040] WC layer: W: 32-55at%, C: 30-58at%;

[0041] WN layer: W: 32-55at%, N: 30-58at%;

[0042] CrNiN layer contains 45-75 at% Cr, 1-15 at% Ni, and 35-70 at% N.

[0043] CrAlN layer contains 20-40 at%, 15-45 at%, and 30-60 at% of Cr;

[0044] In the CrAlNiN layer, Cr: 20-40at%, Al: 20-45at%, Ni: 0.5-15at%, N: 30-60at%;

[0045] In the CrAlW layer, Cr: 15-30at%, Al: 20-45at%, W: 0.5-22at%, N: 23-58at%;

[0046] The TiN layer contains Ti: 50-60 at%, N: 40-50 at%.

[0047] The advantages, main compound compositions, and microstructural characteristics of the above-mentioned transition layers are shown in the following table:

[0048]

[0049]

[0050] In the above-mentioned breaker hammer piston, the transition layer has multiple layers.

[0051] The transition layer of the breaker hammer piston can have multiple layers (two or more layers). The advantages of two adjacent transition layers complement each other. The corresponding transition layer can be designed according to the special working conditions or usage requirements of the breaker hammer piston, thereby increasing the service life of the breaker hammer piston.

[0052] In the above-mentioned breaker hammer piston, the thickness of the bonding layer is in the range of 0.05-2 μm, and the thickness of the hard layer is in the range of 1-5 μm.

[0053] In the above-mentioned breaker hammer piston, the thickness of the bonding layer is in the range of 0.05-2 μm, the thickness of the hard layer is in the range of 1-5 μm, and the thickness of the transition layer is in the range of 1-4 μm.

[0054] Preferably, the thickness of the hard layer is less than 3 μm, the thickness of the transition layer is less than 2 μm, and the thickness of the bonding layer is less than 1 μm.

[0055] In the above-mentioned breaker hammer piston, the piston body includes a head, a middle part and a tail part connected in sequence, and the front and rear sides of the middle part are respectively formed with a front boss and a rear boss protruding outward. The outer surface of the head is fully or partially provided with a strengthening coating, and the outer peripheral surface of the front boss and / or the outer peripheral surface of the rear boss is fully or partially provided with a strengthening coating.

[0056] In the above-mentioned breaker hammer piston, a strengthening coating is provided entirely or partially on the outer side surface of the tail portion.

[0057] A method for preparing a breaker hammer piston by magnetron sputtering, characterized in that it comprises the following steps:

[0058] S1. Piston pretreatment: Mechanically or chemically polish the piston surface to a roughness of Ra ≤ 0.3 μm. Ultrasonic cleaning is then performed using acetone, ethanol, and deionized water for 15 minutes each, three times to thoroughly remove grease and particulate contaminants from the piston surface. The piston is then dried with hot air at 80-120°C and placed in a vacuum chamber.

[0059] S2. Glow cleaning of vacuum chamber: Pump down the vacuum chamber to a basic vacuum degree of ≤5.0×10 -3 Pa, and heat the vacuum chamber to 130-400° to release the internal stress of the piston; introduce argon gas and control the flow rate to 300-500 sccm, adjusting the working gas pressure to 2-4 Pa; apply a substrate bias voltage of -800 to -1200 V, and stimulate argon plasma to bombard the surface for 20-90 minutes to remove the oxide layer and activate the surface;

[0060] S3. Bonding layer implantation: Use high-purity titanium or chromium as the target material, control the argon flow rate to 200-400 sccm, maintain the vacuum degree at 0.5-2.0 Pa, maintain the substrate bias voltage at -100 to -300 V, the target power at 2-5 kW, and the deposition time at 20-40 minutes to form a 50-200 nm bonding layer;

[0061] S4, surface hard layer deposition: set the carbon target power to 3-8kW, substrate bias to -50~-500V, pulse bias duty cycle to 20%-80%; argon flow rate to 300-500sccm, acetylene flow rate to 100-300sccm, gas pressure to maintain 1.0-3.0Pa; deposition temperature to 150-300℃; by adjusting the acetylene / argon ratio and bias energy, control the sp 3 / sp 2 Carbon bond ratio; deposition time 60-240 minutes, deposition thickness 1-5μm, film density >95%;

[0062] S5. Post-treatment and cooling: Under argon protection, keep the temperature at 120-350℃ for 30-60 minutes to release the stress in the film layer; turn off the heating and let the vacuum chamber cool naturally to below 150℃.

[0063] In the above-mentioned preparation method of a breaker piston using magnetron sputtering, step S31, transition layer deposition, is also included between steps S3 and S4: acetylene (C2H2) or methane (CH4) is introduced as a carbon source, with a flow rate maintained at 50-200sccm, mixed with argon; the gas pressure is adjusted to 0.8-2.5Pa, and the substrate bias is maintained at -500 to -800V; the proportion of hydrocarbon gas is gradually increased (10%→80%), while the metal target power is reduced to form various types of gradient transition layers.

[0064] In the above-mentioned method for preparing a breaker piston by using magnetron sputtering, the step S31 is repeated to deposit and generate multiple transition layers of different materials and different thicknesses.

[0065] Compared with the prior art, the technical effects of the present invention are:

[0066] The present invention can significantly increase the friction resistance and service life of the breaker hammer piston by arranging a strengthening coating having a hard layer and a bonding layer on the outer surface of the existing breaker hammer piston. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is a structural schematic diagram of a breaker hammer piston of the present invention.

[0068] Figure 2 This is a schematic cross-sectional view of the strengthening coating of the present invention. Figure 1 .

[0069] Figure 3 This is a schematic cross-sectional view of the strengthening coating of the present invention. Figure 2 .

[0070] Figure 4 It is a process flow chart of the present invention.

[0071] In the figure, 1 is the piston body; 11 is the head; 12 is the middle part; 121 is the front boss; 122 is the rear boss; 13 is the tail; 21 is the hard layer; 22 is the bonding layer; 23 is the transition layer. DETAILED DESCRIPTION

[0072] The technical solutions of the present invention are described in detail below with reference to the examples, but the scope of protection of the present invention is not limited thereto. Experimental methods without specific conditions in the examples are generally carried out under conventional conditions or conditions recommended by the manufacturer.

[0073] Example 1: Breaker piston based on DLC hard layer 21 and preparation method

[0074] 1. Structural characteristics

[0075] The piston body 1 comprises a head portion 11 , a middle portion 12 (with a front boss 121 and a rear boss 122 ) and a tail portion 13 which are connected in sequence. Part of the outer surfaces of the head portion 11 , the front boss 121 and the tail portion 13 are provided with a strengthening coating.

[0076] Strengthen coating structure:

[0077] Bonding layer 22: high-purity Cr layer (Cr content ≥ 85at%), thickness 1μm;

[0078] Hard layer 21: DLC layer (amorphous carbon-based material, sp 3 The hybrid bond accounts for 50%, and the Cr element is doped with 10at%), and the thickness is 3μm.

[0079] 2. Preparation Method

[0080] Step S1 (pretreatment): Mechanically polish the piston surface to a surface roughness of Ra ≤ 0.3 μm; ultrasonically clean the piston using acetone, ethanol, and deionized water (15 minutes each, three cycles) to thoroughly remove grease and particulate contaminants; and after hot air drying at 100°C, place the piston in the vacuum chamber of a magnetron sputtering device.

[0081] Step S2 (glow cleaning): evacuate the vacuum chamber to a basic vacuum degree of ≤5.0×10 -3 Pa, heated to 200 ° C to release the internal stress of the piston; introduced argon gas (flow rate 400 sccm), and adjusted the working gas pressure to 3 Pa; applied a substrate bias voltage of -1000 V, and excited argon plasma to bombard the surface for 90 minutes to remove the oxide layer and activate the surface.

[0082] Step S3 (deposition of bonding layer 22 ): using a high-purity Cr target, an argon flow rate of 300 sccm, and a vacuum degree of 1.5 Pa; setting the target power to 3 kW, the substrate bias voltage to -200 V, and the deposition time to 30 minutes to form the Cr bonding layer 22 .

[0083] Step S4 (deposition of hard layer 21): switch to carbon target, argon flow rate 300 sccm, acetylene flow rate 200 sccm, gas pressure maintained at 2.0 Pa; carbon target power 5 kW, substrate bias -100 V, pulse bias duty cycle 50%; deposition temperature is controlled at 250 ° C, and sp is controlled by adjusting the acetylene / argon ratio. 3 / sp 2 The bonding ratio is 1:1; the deposition time is 180 minutes, and a DLC hard layer 21 with a thickness of 3 μm is formed.

[0084] Step S5 (post-processing): Under argon protection, heat the film at 250° C. for 45 minutes to release the stress in the film layer; turn off the heating system, and naturally cool the vacuum chamber to below 150° C. before removing the piston.

[0085] 3. Technical Effect

[0086] The friction coefficient of the DLC hard layer 21 is reduced to below 0.15, and the wear resistance is significantly improved compared to the uncoated piston; the doping of Cr elements significantly reduces the residual stress of the coating, and the bonding strength between the bonding layer 22 and the substrate is enhanced; it is suitable for high load and dry friction conditions.

[0087] Example 2: Breaker piston with CrN hard layer 21 and CrN bonding layer 22 and preparation method

[0088] 1. Structural characteristics

[0089] Strengthen coating structure:

[0090] Bonding layer 22: CrN layer (Cr: 55at%, N: 45at%), thickness 0.5μm;

[0091] Hard layer 21: CrN layer (Cr: 60 at %, N: 40 at %), thickness 4 μm.

[0092] 2. Preparation Method

[0093] Step S3 (deposition of bonding layer 22): Using a Cr target, nitrogen (N2 flow rate 200 sccm) and argon flow rate 300 sccm were introduced; target power was 4 kW, substrate bias voltage was -150 V, and deposition time was 25 minutes to form a Cr-rich CrN bonding layer 22. Step S4 (deposition of hard layer 21): Maintaining the Cr target, the nitrogen flow rate was increased to 300 sccm; target power was 5 kW, and deposition time was 200 minutes to form a CrN hard layer 21 with a high nitrogen content.

[0094] The remaining steps are the same as those in Example 1.

[0095] 3. Technical Effect

[0096] The Cr2N phase in the bonding layer 22 forms a Cr-Fe solid solution with the matrix, significantly improving the interface bonding strength; the dense CrN structure of the hard layer 21 has greatly improved the salt spray corrosion resistance time; it is suitable for high humidity and marine environments.

[0097] Example 3: Multi-layer coated breaker piston containing WC transition layer 23 and preparation method

[0098] 1. Structural characteristics

[0099] Strengthen coating structure:

[0100] Bonding layer 22: Ti layer (Ti content ≥ 70at%), thickness 1.5μm;

[0101] Transition layer 23: WC layer (W: 45 at %, C: 50 at %), thickness 2 μm;

[0102] Hard layer 21: CrAlN layer (Cr: 30 at %, Al: 25 at %, N: 45 at %), thickness 3 μm.

[0103] 2. Preparation Method

[0104] Step S3 (deposition of bonding layer 22 ): using a Ti target, an argon flow rate of 400 sccm, a target power of 3 kW, and a deposition time of 35 minutes to form a pure Ti bonding layer 22 .

[0105] Step S31 (deposition of transition layer 23): switch to W target, introduce acetylene (C2H2 flow rate 150 sccm) and argon flow rate 300 sccm; target power 4 kW, substrate bias -300 V, deposition time 120 minutes, to form nanocrystalline WC transition layer 23.

[0106] Step S4 (deposition of hard layer 21 ): using a Cr / Al composite target (power ratio 2:1), introducing nitrogen (N2 flow rate 250 sccm); total target power 6 kW, deposition temperature 300° C., deposition time 240 minutes, to form a CrAlN hard layer 21 .

[0107] The remaining steps are the same as those in Example 1.

[0108] 3. Technical Effect

[0109] The WC transition layer 23 has a hardness of 2800HV, significantly improving its impact resistance. The CrAlN hard layer 21 maintains oxidation resistance at 1000°C and is suitable for high-temperature and heavy-load conditions in mines.

[0110] Example 4: Hammer piston with gradient CrAlNiN transition layer 23 and preparation method

[0111] 1. Structural characteristics

[0112] Strengthen coating structure:

[0113] Bonding layer 22: Cr layer (Cr: 60at%), thickness 1μm;

[0114] Transition layer 23: double-layer gradient CrAlNiN (first layer: Cr: 35at%, Al: 30at%, Ni: 5at%, N: 30at%; second layer: Cr: 25at%, Al: 40at%, Ni: 10at%, N: 25at%), total thickness 3μm;

[0115] Hard layer 21: WN layer (W: 50 at %, N: 50 at %), thickness 2 μm.

[0116] 2. Preparation Method

[0117] Step S31 (deposition of transition layer 23): First layer: Use Cr / Al / Ni composite target (power ratio 7:6:1), introduce nitrogen (N2 flow rate 300sccm), and deposition time 90 minutes; Second layer: Adjust the target power ratio to 5:8:2, increase the N2 flow rate to 400sccm, and deposition time 90 minutes.

[0118] Step S4 (deposition of hard layer 21 ): using a W target, introducing nitrogen (N 2 flow rate 350 sccm), target power 5 kW, deposition time 150 minutes, to form a WN hard layer 21 with an amorphous / nanocrystalline mixed structure.

[0119] The remaining steps are the same as those in Example 3.

[0120] 3. Technical Effect

[0121] The gradient transition layer 23 alleviates the difference in thermal expansion coefficient and improves the number of thermal shock resistance cycles; the WN hard layer 21 reduces the friction coefficient and is suitable for high-frequency impact conditions.

[0122] Example 5: Breaker piston based on TiN bonding layer 22 and composite hard layer 21 and preparation method thereof

[0123] 1. Structural characteristics

[0124] Strengthening coating structure: bonding layer 22: TiN layer (Ti: 55at%, N: 45at%), thickness 0.8μm;

[0125] Hard layer 21: composite structure (inner layer DLC doped with 15at% Si, outer layer CrN layer), total thickness 4 μm.

[0126] 2. Preparation Method

[0127] Step S3 (deposition of bonding layer 22 ): a Ti target is used, nitrogen gas (N 2 flow rate 250 sccm) is introduced, target power is 4 kW, and deposition time is 30 minutes to form a cubic phase TiN bonding layer 22 .

[0128] Step S4 (deposition of hard layer 21): inner layer: carbon target power 6kW, Si target power 0.5kW, acetylene flow 200sccm, deposition time 120 minutes; outer layer: switch to Cr target, introduce nitrogen (N2 flow 300sccm), target power 5kW, deposition time 90 minutes.

[0129] The remaining steps are the same as those in Example 1.

[0130] 3. Technical Effect

[0131] The Si-doped DLC layer inhibits metal transfer and improves anti-adhesion properties; the composite coating reduces the friction coefficient under dry friction conditions and is suitable for scenarios where engineering machinery lacks lubrication.

[0132] Example 6: Ultra-thick CrAlW hard layer 21 breaker hammer piston and preparation method

[0133] 1. Structural characteristics

[0134] Strengthen coating structure:

[0135] Bonding layer 22: CrN layer (Cr: 50at%, N: 50at%), thickness 1μm;

[0136] Hard layer 21: CrAlW layer (Cr: 20 at %, Al: 35 at %, W: 15 at %, N: 30 at %), thickness 5 μm.

[0137] 2. Preparation Method

[0138] Step S4 (deposition of hard layer 21): Use Cr / Al / W composite target (power ratio 4:7:3), introduce nitrogen (N2 flow rate 350sccm); total target power 8kW, deposition temperature 350℃, deposition time 300 minutes, to form a CrAlW layer of amorphous matrix + nanocrystalline hard phase.

[0139] The remaining steps are the same as those in Example 2.

[0140] 3. Technical Effect

[0141] The CrAlW hard layer 21 has a hardness of 3500HV, which improves extreme wear resistance; the high-temperature strength is maintained up to 1200℃, making it suitable for high-temperature impact environments.

[0142] Example 7: Simplified structure breaker piston without transition layer 23 and preparation method

[0143] 1. Structural characteristics

[0144] Strengthen coating structure:

[0145] Bonding layer 22: Cr layer (Cr: 100at%), thickness 0.5μm;

[0146] Hard layer 21: CrN layer (Cr: 50 at %, N: 50 at %), thickness 2 μm.

[0147] 2. Preparation Method

[0148] The transition layer 23 deposition step ( S31 ) is omitted, and the bonding layer 22 and the hard layer 21 are deposited directly;

[0149] Step S3: depositing a pure Cr bonding layer 22 (Cr target power 3 kW, deposition time 20 minutes);

[0150] Step S4: depositing a CrN hard layer 21 (Cr target power 5 kW, N2 flow rate 300 sccm, deposition time 120 minutes).

[0151] The remaining steps are the same as those in Example 2.

[0152] 3. Technical Effect

[0153] The process time is shortened and the cost is reduced; it is suitable for conventional impact loads and medium and low temperature conditions.

[0154] The present invention achieves the following comprehensive advantages through the multi-layer design of the bonding layer 22, the transition layer 23 and the hard layer 21, combined with the precise control of the magnetron sputtering process parameters:

[0155] Mechanical properties: coating hardness ranges from 1500 to 3800 HV, and wear resistance is increased by 40% to 60%;

[0156] Interface bonding: a diffusion transition layer 23 is formed between the bonding layer 22 and the substrate, and the bonding strength is increased by 30%-50%;

[0157] Adaptability to working conditions: Suitable for complex scenarios such as high temperature (≤1200℃), high humidity, dry friction, and high-frequency impact;

[0158] Process flexibility: By adjusting material combination, layer thickness and deposition parameters, it can be customized to meet different industrial needs.

[0159] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection defined by the claims of the present invention.

Claims

1. A breaker hammer piston, comprising a piston body (1), wherein the outer surface of the piston body (1) is entirely or partially provided with a strengthening coating, characterized in that: The strengthening coating comprises a hard layer (21) and a bonding layer (22), wherein the bonding layer (22) is connected to the piston body (1), and the hard layer (21) is located outside the bonding layer (22). The hard layer (21) is a DLC layer, a CrN layer, a WC layer, a WN layer, a CrNiN layer, a CrAlN layer, a CrAlNiN layer, or a CrAlW layer. The DLC layer of the hard layer (21) is composed of an amorphous carbon-based material, wherein sp 3 The hybrid bond accounts for 40%-60%, and is doped with 1%-20% of metal or non-metal elements, the elements are Cr, Si, W, F, N, B, and their mass fraction is 0.5%-15%, The CrN layer of the hard layer (21) contains 45-75 at% Cr and 35-70 at% N; The WC layer of the hard layer (21) has W: 32-55at%, C: 30-58at% In the WN layer of the hard layer (21), W: 32-55at%, N: 30-58at% The CrNiN layer of the hard layer (21) comprises 45-75 at%, 1-15 at%, and 35-70 at% of Cr; The CrAlN layer of the hard layer (21) comprises 20-40 at%, 15-45 at%, and 30-60 at% of Cr; The CrAlNiN layer of the hard layer (21) comprises 20-40 at%, 20-45 at%, 0.5-15 at%, and 30-60 at% of Cr; The CrAlW layer of the hard layer (21) comprises 15-30 at%, 20-45 at%, 0.5-22 at%, and 23-58 at% of Cr; The bonding layer (22) is a Cr layer, a Ti layer, a TiN layer, or a CrN layer. The Cr layer of the bonding layer (22) contains 40-100 at% Cr. Ti in the Ti layer of the bonding layer (22): 40-100at% The TiN layer of the bonding layer (22) contains 50-60 at% Ti and 40-50 at% N; The CrN layer of the bonding layer (22) contains 45-60 at% Cr and 40-55 at% N.

2. A breaker hammer piston according to claim 1, characterized in that: The strengthening coating comprises a transition layer, the transition layer being arranged between the hard layer (21) and the bonding layer (22), the transition layer being a CrN layer, a WC layer, a WN layer, a CrNiN layer, a CrAlN layer, a CrAlNiN layer, a CrAlW layer, or a TiN layer. CrN layer: Cr: 45-75at%, N: 35-70at%; WC layer: W: 32-55at%, C: 30-58at%; WN layer: W: 32-55at%, N: 30-58at%; CrNiN layer contains 45-75 at% Cr, 1-15 at% Ni, and 35-70 at% N. CrAlN layer contains 20-40 at%, 15-45 at%, and 30-60 at% of Cr; In the CrAlNiN layer, Cr: 20-40at%, Al: 20-45at%, Ni: 0.5-15at%, N: 30-60at%; In the CrAlW layer, Cr: 15-30at%, Al: 20-45at%, W: 0.5-22at%, N: 23-58at%; The TiN layer contains Ti: 50-60 at%, N: 40-50 at%.

3. A breaker hammer piston according to claim 2, characterized in that: The transition layer has multiple layers.

4. A breaker hammer piston according to claim 1, characterized in that: The thickness of the bonding layer (22) is in the range of 0.05-2 μm, and the thickness of the hard layer (21) is in the range of 1-5 μm.

5. A breaker hammer piston according to claim 2, characterized in that: The thickness of the bonding layer (22) is in the range of 0.05-2 μm, the thickness of the hard layer (21) is in the range of 1-5 μm, and the thickness of the transition layer is in the range of 1-4 μm.

6. A breaker hammer piston according to any one of claims 1 to 5, characterized in that: The piston body (1) comprises a head (11), a middle part (12) and a tail part (13) connected in sequence, and the front and rear sides of the middle part (12) are respectively formed with a front boss (121) and a rear boss (122) protruding outwards, and the outer surface of the head (11) is entirely or partially provided with a strengthening coating, and the outer peripheral surface of the front boss (121) and / or the outer peripheral surface of the rear boss (122) are entirely or partially provided with a strengthening coating.

7. A breaker hammer piston according to claim 6, characterized in that: A strengthening coating is entirely or partially provided on the outer side surface of the tail portion (13).

8. A method for preparing a breaker hammer piston by magnetron sputtering, characterized in that: The steps include: S1. Piston pretreatment: Mechanically or chemically polish the piston surface to a roughness of Ra ≤ 0.3 μm. Ultrasonic cleaning is then performed using acetone, ethanol, and deionized water for 15 minutes each, three times to thoroughly remove grease and particulate contaminants from the piston surface. The piston is then dried with hot air at 80-120°C and placed in a vacuum chamber. S2. Glow cleaning of the vacuum chamber: evacuate the vacuum chamber to a basic vacuum degree of ≤5.0×10-3Pa, and heat the vacuum chamber to 130-400° to release the internal stress of the piston; introduce argon gas and control the flow rate to 300-500sccm, and adjust the working pressure to 2-4Pa; Apply a substrate bias voltage of -800 to -1200 V and excite argon plasma to bombard the surface for 20 to 90 minutes to remove the oxide layer and activate the surface; S3, bonding layer (22) implantation: using high-purity titanium or chromium as a target material, controlling the argon flow rate to 200-400 sccm, maintaining the vacuum degree at 0.5-2.0 Pa, maintaining the substrate bias voltage at -100 to -300 V, the target power at 2-5 kW, and the deposition time at 20-40 minutes to form a 50-200 nm bonding layer (22); S4, surface hard layer (21) deposition: set the carbon target power to 3-8kW, substrate bias to -50 to -500V, pulse bias duty cycle to 20%-80%; argon flow rate to 300-500sccm, acetylene flow rate to 100-300sccm, gas pressure to maintain 1.0-3.0Pa; deposition temperature to 150-300℃; by adjusting the acetylene / argon ratio and bias energy, control sp 3 / sp 2 Carbon bond ratio; deposition time 60-240 minutes, deposition thickness 1-5μm, film density >95%; S5. Post-treatment and cooling: Under argon protection, keep the temperature at 120-350℃ for 30-60 minutes to release the stress in the film layer; turn off the heating and let the vacuum chamber cool naturally to below 150℃.

9. The method for preparing a breaker hammer piston by magnetron sputtering according to claim 8, characterized in that: Between steps S3 and S4, step S31, transition layer deposition, is also included: acetylene (C2H2) or methane (CH4) is introduced as a carbon source, with a flow rate maintained at 50-200 sccm, mixed with argon; the gas pressure is adjusted to 0.8-2.5 Pa, and the substrate bias is maintained at -500 to -800 V; the proportion of hydrocarbon gas is gradually increased (10%→80%), while the metal target power is reduced to form various types of gradient transition layers (23).

10. The method for preparing a breaker hammer piston by magnetron sputtering according to claim 9, characterized in that: This step is repeated in step S31 to deposit and generate multiple transition layers (23) of different materials and different thicknesses.

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