Zinc-tin alloy rotating target material preparation process based on thermal spraying process

Abstract

The invention relates to a zinc-tin alloy rotating target material preparation process based on a thermal spraying process. The zinc-tin alloy rotating target material preparation process comprises the following steps: (a) providing a pure zinc wire and a pure tin wire as raw materials; (b) the stainless steel back pipe is pretreated; (c) setting flame thermal spraying process parameters; (d) double-wire synchronous spraying is carried out; (e) dynamic component control: adjusting the wire supply speed according to the target alloy proportion; (f) temperature control: maintaining the surface temperature of the target material through back pipe water cooling and surface nitrogen cooling; and (g) post-processing: turning and polishing to obtain the final target material layer. According to the zinc-tin alloy rotating target material preparation process based on the thermal spraying process, a zinc-tin alloy wire material is replaced with pure zinc and pure tin wire materials, so that the production cost is reduced, and the size, purity, density and the like of the zinc-tin alloy target material meet the requirements of a subsequent sputter coating process; and the thermal spraying process for preparing the zinc-tin alloy target material is simple and low in cost.

Description

Technical Field

[0001] The present invention relates to a process for preparing a high-density zinc-tin rotating target by flame thermal spraying, belonging to the technical field of metal target manufacturing Background Art

[0002] In the construction field, the issue of energy consumption has always been highly concerned. According to statistical data, 25%-35% of the energy consumption in buildings is caused by insufficient window performance. Especially in China's building energy consumption system, the energy consumption per unit building area is 2-3 times higher than that of developed countries, and the heat transfer coefficient per unit area of the outer window even reaches more than 3.0 W / (m 2 ·K), far exceeding the current EU standard limit of 1.1 W / (m 2 ·K). This directly results in 40% of the heat load in China's building cooling demand penetrating through the window system. Therefore, improving the performance of the outer window has become a crucial and very effective measure for energy conservation

[0003] For building outer windows, reducing solar radiant heat can reduce the consumption of indoor air conditioners and achieve energy conservation in buildings. Energy-saving outer window technologies represented by low-emissivity coated glass (Low-E glass) have emerged as the times require. This technology constructs a functional thin film system on the glass surface, achieving a visible light transmittance of more than 80% while increasing the mid- and far-infrared radiation reflectivity to 75%-85%. Its unique "warm in winter and cool in summer" characteristic can reduce the building air-conditioning energy consumption by 30%-40%

[0004] The key reason why LOW-E glass can achieve these functions lies in the deposition of multiple functional films on the glass surface, such as transparent conductive layers, infrared reflection layers, etc. to achieve high light transmittance and low thermal radiation transmittance. And zinc-tin alloy targets play an indispensable role in the process of preparing these functional films. Zinc-tin alloy targets are mainly used for large-area glass coating through physical vapor deposition processes. In this process, the quality of the sputtering target has a direct and crucial impact on film deposition and film layer quality

[0005] Currently, the common zinc-tin alloy targets are mainly produced by casting. However, due to the significant difference in the melting points of zinc and tin, traditional melting processes are prone to serious segregation of the target composition (such as tin-rich on the target surface and zinc-rich inside). At the same time, during the cooling process of the ingot, it is necessary to strictly control the cooling rate and subsequent heat treatment processes to eliminate columnar dendritic structures, prevent cracking, and affect the uniformity of sputtering coating

[0006] The powder metallurgy process prepares zinc-tin alloy powder through atomization and then through sintering. However, during the powder preparation process, the powder is extremely prone to oxidation, and the oxide layer on the powder surface will form grain boundary inclusions during the sintering process, increasing the resistivity of the target and thus reducing the performance of the target

[0007] Therefore, the thermal spraying process has been developed in the industry, which directly deposits zinc-tin alloy wire into a profiled target under the protection of inert gas. The oxygen content of its deposited layer can be controlled below 1500 ppm, and the composition fluctuation is small. Due to its high spraying efficiency, uniform chemical composition, fine grain size, and controllable target shape and size, etc., it has become an ideal process technology for preparing zinc-tin alloy targets.

[0008] However, the processing of zinc-tin alloy wire faces various technical problems, mainly due to the physical and chemical property differences between zinc and tin (such as melting point, elongation rate, solidification shrinkage rate, etc.) and the oxidation and gasification during the processing, resulting in a relatively high price of the finished alloy wire. Therefore, a new thermal spraying target preparation process is needed to prepare high-density and low-cost zinc-tin alloy targets that meet the requirements of large-size sputtering coating. Summary of the Invention

[0009] The purpose of the present invention is to overcome the above deficiencies and provide a preparation process for a zinc-tin alloy rotating target based on the thermal spraying process. By using pure zinc and pure tin wires to replace zinc-tin alloy wires, the production cost is reduced, and the size, purity, density, etc. of the zinc-tin alloy target meet the requirements of subsequent sputtering coating processes. Moreover, the thermal spraying process for preparing the zinc-tin alloy target is simple and has a low cost.

[0010] The purpose of the present invention is achieved as follows:

[0011] A preparation process for a zinc-tin alloy rotating target based on the thermal spraying process,

[0012] including the following steps:

[0013] (a) Provide pure zinc wire and pure tin wire as raw materials. The purity of the pure zinc wire is ≥99.8%, and the diameter is 2.5 ± 0.04 mm. The purity of the pure tin wire is ≥99.99%, and the diameter is 2.5 ± 0.04 mm;

[0014] (b) Pretreat the stainless steel back tube: successively perform alcohol cleaning, steel sand blasting, and spray a bonding layer with a thickness of 0.3 - 0.5 mm;

[0015] (c) Set the process parameters of flame thermal spraying: the methane flow rate is 35 - 50 L / min, the oxygen flow rate is 60 - 100 L / min, the nitrogen protective gas flow rate is 500 - 800 L / min, and maintain the volume ratio of methane to oxygen at 1:1.8 - 2.2;

[0016] (d) Synchronous double-wire spraying: control the rotation speed of the back tube at 100 - 200 rpm, the spray gun reciprocates along the axial direction of the back tube at a speed of 350 - 650 mm / min, the distance between the spray gun and the back tube is 50 - 100 mm, and keep the spray gun horizontal and perpendicular to the back tube;

[0017] (e) Dynamic component control: Adjust the wire feeding speed according to the target alloy ratio;

[0018] (f) Temperature control: Maintain the surface temperature of the target at 80 - 110 °C through water cooling of the back tube and nitrogen cooling of the surface;

[0019] (g) Post - treatment: Turning and polishing to obtain a surface roughness of Ra 3 - 5 μm, the final thickness of the target layer is 13 mm, and the porosity is ≤5.0%.

[0020] Preferably, in step (e), the relationship between the target alloy ratio and the adjusted wire feeding speed is as follows:

[0021] Zinc 50 wt. % / Tin 50 wt. % combination: The feeding speed of the zinc wire is 65 - 75 mm / s, and the feeding speed of the tin wire is 45 - 55 mm / s

[0022] Zinc 60 wt. % / Tin 40 wt. % combination: The feeding speed of the zinc wire is 75 - 85 mm / s, and the feeding speed of the tin wire is 40 - 50 mm / s.

[0023] Preferably, in step (f), the temperature of the cooling water in the back tube is 60 - 70 °C, the flow rate of the back tube cooling water is 18 - 22 L / min; the gas flow rate of the nitrogen cooling is 50 - 100 L / min.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The present invention forms a zinc - tin alloy target layer surrounding the base tube by using a flame thermal spraying process, and obtains a high - density zinc - tin rotating target with dimensions and composition meeting the requirements of sputtering coating, high density, and no obvious composition segregation. Detailed implementation manners

[0026] The present invention relates to a preparation process of a zinc - tin alloy rotating target based on a thermal spraying process. By simultaneously performing flame thermal spraying on zinc wire and tin wire, a high - density zinc - tin alloy rotating target is prepared; the purity of the pure zinc wire is greater than or equal to 99.8%, the diameter is 2.5 ± 0.04 mm, the purity of the pure tin wire is greater than or equal to 99.99%, and the wire diameter is 2.5 ± 0.04 mm.

[0027] Among them: Flame thermal spraying is based on a high - temperature flame generated by the combustion of gases such as methane or acetylene as the heat source. After the pure zinc wire and pure tin wire enter the flame jet, they will quickly melt under the action of the high - temperature flame jet, and accelerate and impact towards the back tube direction at high speed with the help of the protective gas. The back tube material is 304 stainless steel or 316 stainless steel.

[0028] Since the melting point of pure zinc wire is about 419°C and that of pure tin wire is 232°C, the tin wire will melt first and wrap the zinc droplets. After the high-speed molten zinc-tin particles impact the substrate surface, they will quickly spread, cool, and solidify alloying, stacking layer by layer on the substrate to form the target.

[0029] And during the whole process, by adjusting the wire feeding ratio, zinc-tin alloy targets with different component ratios can be obtained. During the deposition process, due to the continuous impact of subsequent particles, the already deposited particles will be further compacted to form a dense target structure.

[0030] As the deposition process continues, the thickness of the zinc-tin target gradually increases until the required size is reached. The thickness of the zinc-tin layer of the target is 13 mm.

[0031] Preferably, during the wire feeding process, if the wire feeding speed of the zinc wire is too fast, the zinc wire will not be completely melted, so that it cannot effectively combine with the tin droplets, and at the same time, the uncompletely melted zinc particles cannot effectively combine with the substrate, resulting in defects or composition deviation.

[0032] Preferably, in the high-temperature flame jet, since the vaporization temperature of the zinc wire is 907°C and that of the tin wire is 2602°C, zinc is more likely to vaporize to form zinc vapor, which is then carried away by the negative pressure dust collection system, causing composition deviation and reducing the spraying efficiency at the same time. Therefore, controlling the wire feeding rates of the pure zinc wire and the pure tin wire, as well as the heat of the flame spray gun, is the key to mass-producing zinc-tin alloy targets with different compositions efficiently.

[0033] Preferably, the process gas for flame thermal spraying is a mixed gas of methane and oxygen, and nitrogen is used as the protective gas to accelerate the molten zinc-tin droplets. To prevent the target from oxidation, nitrogen is also needed to cool the target. The flow rate of methane is 35 - 50 L / min, the flow rate of oxygen is 60 - 100 L / min, the flow rate of the nitrogen protective gas is 500 - 800 L / min, and the flow rate of the nitrogen cooling gas is 50 L / min to 100 L / min. To ensure the complete combustion of methane, the ratio of methane to oxygen needs to be about 1:2 to ensure the smooth melting and deposition of the pure zinc wire and the pure tin wire on the target. The wire feeding speed is the key to obtaining zinc-tin alloy targets with corresponding compositions. The present invention relates to zinc-tin alloy targets with two components. Component one is 50% zinc and 50% tin. For this component target, the wire feeding speed of the tin wire needs to be controlled at 45 - 55 mm / s, and the wire feeding speed of the zinc wire needs to be controlled at 65 - 75 mm / s. Component two is 60% zinc and 40% tin. For this component target, the wire feeding speed of the tin wire needs to be controlled at 40 - 50 mm / s, and the wire feeding speed of the zinc wire needs to be controlled at 75 - 85 mm / s.

[0034] Preferably, before thermal spraying, the back tube needs to be pretreated, including the following steps: checking whether the back tube runout and thickness are normal, and cleaning the surface of the back tube with industrial alcohol. After cleaning, the surface of the back tube is sandblasted with steel sand. After sandblasting, a bonding layer also needs to be sprayed on the surface. This bonding layer bonds the zinc-tin alloy to the back tube by mechanical bonding and metallurgical bonding methods, and the thickness of the bonding layer needs to be 0.3 mm to 0.5 mm.

[0035] Meanwhile, during the spraying process, the back tube rotates around the central axis at a speed of 100 rpm to 200 rpm. Water is passed through the back tube for cooling, the temperature of the cooling water in the back tube is 60 - 70 °C, the flow rate of the cooling water in the back tube is 18 - 22 L / min, and at the same time, nitrogen is used externally to cool the surface of the zinc-tin alloy target, and the surface temperature of the zinc-tin alloy target is controlled at 80 °C to 110 °C.

[0036] While the back tube is rotating, the thermal spraying gun reciprocates uniformly along the axial direction of the back tube at a speed of 350 mm / min to 650 mm / min. The distance from the gun to the back tube is 50 mm to 100 mm, and the nozzle of the gun needs to be horizontally perpendicular to the back tube.

[0037] After spraying, the target needs to be turned and polished to achieve the required surface roughness. The surface roughness after polishing is generally Ra3 μm to Ra5 μm.

[0038] The purity of the target after spraying is greater than or equal to 99.8%. The length of the target can be customized according to customer requirements. The size of the target is 13 mm, and the porosity of the target is less than or equal to 5.0%.

[0039] By the above method of the present invention, a zinc-tin alloy target layer surrounding the back tube is formed by the flame thermal spraying process, and a high-density zinc-tin rotating target with dimensions and composition meeting the requirements of sputtering coating, high density, and no obvious composition segregation can be obtained.

[0040] The following are two embodiments based on the method of this patent:

[0041] Embodiment 1:

[0042] Target composition: Zn 50 wt.%, Sn 50 wt.%.

[0043] The process gas is a mixed gas of methane and oxygen. The flow rate of methane is 35 L / min, the flow rate of oxygen is 72 L / min, and the flow rate of the nitrogen protection gas is 640 L / min.

[0044] During the spraying process, the back tube rotates around the central axis at a speed of 150 rpm. Water is circulated inside the back tube for cooling, and nitrogen is used externally to cool the surface of the zinc-tin alloy target. The gas flow rate of nitrogen cooling is 70 L / min, and the surface temperature of the target is controlled at 80 °C.

[0045] The thermal spraying gun reciprocates uniformly along the axial direction of the base tube at a speed of 400 mm / min. The distance between the gun and the base tube is 80 mm, and the spray gun nozzle needs to be perpendicular to the back tube.

[0046] In this specific example, the density of the zinc-tin alloy target is 6.84 g / cm3, the target purity is 99.86%, the zinc content is 50.4 wt.%, the tin content is 49.6 wt.%, the oxygen content is 760 ppm, and the nitrogen content is 10 ppm.

[0047] Example Two:

[0048] Target composition: Zn 60 wt.%, Sn 40 wt.%.

[0049] The process gas is a mixed gas of methane and oxygen. The flow rate of methane is 45 L / min, the flow rate of oxygen is 87 L / min, and the gas flow rate of nitrogen protection is 750 L / min.

[0050] During the spraying process, the back tube rotates around the central axis at a speed of 150 rpm. Water is circulated inside the back tube for cooling, and nitrogen is used externally to cool the surface of the zinc-tin alloy target. The gas flow rate of nitrogen cooling is 80 L / min, and the surface temperature of the target is controlled at 95 °C.

[0051] The thermal spraying gun reciprocates uniformly along the axial direction of the base tube at a speed of 400 mm / min. The distance between the gun and the base tube is 80 mm, and the spray gun nozzle needs to be perpendicular to the back tube.

[0052] In this specific example, the density of the zinc-tin alloy target shown is 6.71 g / cm3, the target purity is 99.85%, the zinc content is 61.2 wt.%, the tin content is 38.8 wt.%, the oxygen content is 1002 ppm, and the nitrogen content is 13 ppm.

[0053] In addition: It should be noted that the above specific implementation manners are only an optimized solution of this patent. Any changes or improvements made by those skilled in the art based on the above concepts are within the protection scope of this patent.

Claims

1. A preparation process of a zinc-tin alloy rotating target based on a thermal spraying process, characterized in that: It includes the following steps: (a) Provide pure zinc wire and pure tin wire as raw materials. The purity of the pure zinc wire is ≥99.8% and the diameter is 2.5±0.04 mm. The purity of the pure tin wire is ≥99.99% and the diameter is 2.5±0.04 mm; (b) Pretreat the stainless steel back tube: successively perform alcohol cleaning, steel grit sandblasting, and spray a bonding layer with a thickness of 0.3-0.5 mm; (c) Set the flame thermal spraying process parameters: methane flow rate 35-50 L / min, oxygen flow rate 60-100 L / min, nitrogen protective gas flow rate 500-800 L / min, and maintain the volume ratio of methane to oxygen at 1:1.8-2.2; (d) Dual-wire synchronous spraying: control the rotation speed of the back tube at 100-200 rpm, the spray gun reciprocates along the axial direction of the back tube at a speed of 350-650 mm / min, the spray gun is 50-100 mm away from the back tube, and keep the spray gun horizontal and perpendicular to the back tube; (e) Dynamic composition control: adjust the wire feeding speed according to the target alloy ratio; (f) Temperature control: maintain the surface temperature of the target at 80-110 °C through water cooling of the back tube and surface nitrogen cooling; (g) Post-treatment: turn and polish to obtain a surface roughness of Ra3-5 μm, the final thickness of the target layer is 13 mm, and the porosity is ≤5.0%.

2. The preparation process of the zinc-tin alloy rotary target based on the thermal spraying process according to claim 1, characterized in that: In step (e), the relationship between the target alloy ratio and the adjusted wire feeding speed is: Zinc 50wt.% / Tin 50wt.% combination: zinc wire feeding speed 65-75 mm / s, tin wire feeding speed 45-55 mm / s Zinc 60wt.% / Tin 40wt.% combination: zinc wire feeding speed 75-85 mm / s, tin wire feeding speed 40-50 mm / s.

3. The preparation process of a zinc-tin alloy rotating target based on a thermal spraying process according to claim 1, characterized in that: In step (f), the temperature of the cooling water in the back tube is 60-70 °C, the cooling water flow rate of the back tube is 18-22 L / min; the gas flow rate of nitrogen cooling is 50-100 L / min.