Erosion-resistant reinforced coating method for accessories of measurement-while-drilling instrument for petroleum drilling

Abstract

The invention provides an erosion-resistant reinforced coating method for a petroleum drilling measurement-while-drilling instrument accessory, which comprises the following steps: S1, pretreating a workpiece, and analyzing the specification and model, the accessory size, the use environment and the wear mechanism of the workpiece; s2, flaw detection is conducted on the workpiece; s3, the surface of the workpiece is cleaned, and the surface roughness is increased through sand blasting treatment till the surface roughness range of the workpiece is 4.0-4.2 microns; s4, a plasma flame spraying system and bismuth alloy powder are used for spraying the workpiece, so that the bismuth alloy powder is evenly attached to the surface of the workpiece to form a bismuth alloy coating, the thickness of the bismuth alloy coating is larger than 0.35 mm, and the bonding strength reaches 40 MPa; and S5, the sprayed coating is subjected to sealing treatment till the porosity of the sprayed coating is reduced to be within 0.5%. The use efficiency of instrument accessories is effectively improved, the purchase and maintenance cost is saved, and the service life of the instrument accessories is prolonged.

Description

Technical Field

[0001] The present invention relates to a method for strengthening a coating, and particularly to a method for erosion-resistant strengthening of accessories for oil drilling measurement-while-drilling instruments. Background Art

[0002] In the field of oil and gas exploration, during the drilling process of each oilfield company, each directional well company undertakes directional technical services for each directional well or horizontal well, and various accessories for oil drilling measurement-while-drilling instruments are used, including conventional directional instruments, rotary steerable systems, near-bit gamma rays, resistivity, etc. During the use of these accessories, due to factors such as harsh downhole working conditions, complex geological conditions, and unstable instrument performance, problems such as rapid wear and high consumption of some instruments and accessories occur. And due to the short service life, unnecessary multiple trips are caused. During the maintenance process after the instrument is returned to the factory, problems such as reduced size of the instrument or accessory and severe mud erosion that cannot be repaired are often found. In order to overall improve the use efficiency of the instrument, save procurement and maintenance costs, and extend the service life, therefore, there is an urgent need in the industry to propose a new erosion-resistant coating for accessories of oil drilling measurement-while-drilling instruments, so as to ensure the satisfaction of production and operation, and further achieve the purpose of cost reduction and efficiency increase. However, the base materials of such directional instrument accessories for oil drilling measurement-while-drilling instruments are mostly beryllium copper or alloys, with a working pressure > 100 Mpa, a working temperature within 150 °C, a working temperature of high-temperature instruments within 175 °C, and they need to withstand the erosion, wear, and chemical corrosion of oil and gas products by water-based mud or oil-based mud. The existing strengthening coating methods cannot meet their actual application requirements. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for erosion-resistant strengthening of accessories for oil drilling measurement-while-drilling instruments, aiming to meet the actual application requirements of such directional instrument accessories for oil drilling measurement-while-drilling instruments, so as to improve the use efficiency of instrument accessories, save procurement and maintenance costs, and extend their service life.

[0004] To this end, the present invention provides a method for erosion-resistant strengthening of accessories for oil drilling measurement-while-drilling instruments, including the following steps:

[0005] Step S1, preprocess the workpiece, and analyze its specification model, accessory size, use environment, and wear mechanism;

[0006] Step S2, perform flaw detection on the workpiece, including penetrant inspection and ultrasonic inspection, to ensure the integrity of the performance of the workpiece base material;

[0007] Step S3, clean the surface of the workpiece, remove the oxide layer, and increase the surface roughness through sandblasting until the surface roughness range of the workpiece is 4.0 - 4.2 μm;

[0008] Step S4: Use a plasma flame spraying system and bismuth alloy powder to spray the workpiece, so that the bismuth alloy powder uniformly adheres to the surface of the workpiece to form a bismuth alloy coating. The thickness of the bismuth alloy coating is greater than 0.35 mm, and the bonding strength reaches 40 MPa.

[0009] Step S5: Seal the sprayed coating until the porosity of the sprayed coating is reduced to less than 0.5%.

[0010] A further improvement of the present invention is that in the step S1, the use environment of the workpiece includes at least one of displacement, pump pressure, and mud density to correspond to the drilling conditions of the workpiece, and the erosion loss of the outer surface of the instrument caused by the flushing of the drilling fluid is associated as the wear mechanism.

[0011] A further improvement of the present invention is that the step S5 includes the following sub-steps:

[0012] Step S501: Attach a sealant to the treatment part of the workpiece, place the workpiece with the attached sealant in a pressurized container, input compressed air for pressurization treatment, pressurize to 1.5 MPa, and maintain for more than 2 hours.

[0013] Step S302: Use an electric control method to heat up the workpiece, heat up to 95 - 100 °C, and maintain for 1.5 - 2 hours.

[0014] A further improvement of the present invention is that in the step S501, the pressurization treatment is up to 1.5 ± 0.1 MPa and maintained for 2.3 - 2.5 hours.

[0015] A further improvement of the present invention is that in the step S502, during the maintenance process of heating up to 95 - 100 °C, continue the pressurization treatment, and pressurize to 1.2 ± 0.05 MPa.

[0016] A further improvement of the present invention is that the step S2 includes the following sub-steps:

[0017] Step S201: Clean and dry the workpiece, and after the drying treatment, perform penetration through a penetrant and observe through a developer.

[0018] Step S202: Transmit ultrasonic signals from the probe to the workpiece, perform wave amplitude recovery through a detector, and analyze the recovered wave amplitude to determine whether there are defects or cracks in the workpiece.

[0019] A further improvement of the present invention is that in the step S202, the surface and internal defects of the workpiece are detected by combining high-frequency ultrasonic signals and low-frequency ultrasonic signals respectively.

[0020] A further improvement of the present invention lies in that in step S3, the surface of the workpiece is first cleaned, including removing the rust by a scraper, cleaning by a wire brush, and polishing by a coarse sand cloth, alone or in combination, to remove the oxide layer; then, sandblasting is performed to increase the surface roughness, and the surface roughness is detected in real time during the sandblasting process. When the surface roughness of the workpiece ranges from 4.0 to 4.2 μm, the sandblasting is stopped and the process jumps to step S4.

[0021] A further improvement of the present invention lies in that in step S4, the bismuth alloy powder includes metallic bismuth powder and auxiliary metal powder, and the auxiliary metal powder includes any one or several of metallic tin powder, metallic lead powder, metallic antimony powder, and metallic indium powder.

[0022] A further improvement of the present invention lies in that in step S4, a spraying parameter table is preset. For each specification model, fitting size, usage environment, and wear mechanism of the workpiece, the corresponding composition and proportion of the bismuth alloy powder are preset; during the actual spraying process, the composition and proportion of the bismuth alloy powder are determined according to the current usage environment.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: First, the workpiece is pre-treated, and its specification model, fitting size, usage environment, and wear mechanism are analyzed, so as to conduct targeted analysis in combination with drilling parameters according to the usage environment and working conditions of various workpieces; then, the workpiece is subjected to flaw detection, including penetrant inspection and ultrasonic flaw detection, to ensure the integrity of the base material performance of the workpiece; the surface of the workpiece is cleaned to remove the oxide layer, and the surface roughness is increased by sandblasting until the surface roughness of the workpiece ranges from 4.0 to 4.2 μm, to increase the coating adhesion for subsequent spraying treatment; then, the workpiece is sprayed using a plasma flame spraying system and bismuth alloy powder, so that the bismuth alloy powder is evenly adhered to the surface of the workpiece to form a bismuth alloy coating. The thickness of the bismuth alloy coating is greater than 0.35 mm, and the bonding strength reaches 40 MPa, to increase the surface impact resistance and hardness of the coating; finally, the sprayed coating is sealed until the porosity of the sprayed coating is reduced to less than 0.5%, so as to well meet the actual application requirements of this kind of directional instrument fitting for the accessories of the oil drilling measurement-while-drilling instrument. The present invention provides a new method for the erosion-resistant strengthening coating of the accessories of the oil drilling measurement-while-drilling instrument, effectively improving the usage efficiency of the instrument accessories, saving the procurement and maintenance costs, and extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the working process of an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] In the description of the present invention, if orientation descriptions are involved, such as "upper", "lower", "front", "rear", "left", "right", etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. If a technical feature is referred to as "set", "fixed", "connected", "installed" on another technical feature, it can be directly set, fixed, connected, or installed on another technical feature, or indirectly set, fixed, connected, or installed on another technical feature.

[0026] In the description of the present invention, if "several" is involved, its meaning is more than one; if "multiple" is involved, its meaning is more than two; if "greater than", "less than", "exceeding" are involved, they should all be understood as not including the present number; if "above", "below", "within" are involved, they should all be understood as including the present number. If "first", "second", etc. are involved, they should be understood as only for distinguishing the names of the same or similar technical features, and cannot be understood as implying / indicating the relative importance of the technical features, cannot be understood as implying / indicating the quantity of the technical features, nor can it be understood as implying / indicating the sequence relationship of the technical features.

[0027] The following further describes in detail the preferred embodiments of the present invention with reference to the accompanying drawings.

[0028] As Figure 1 shown, this embodiment provides a method for an erosion-resistant and strengthening coating for accessories of a measurement-while-drilling instrument in oil drilling, including the following steps:

[0029] Step S1: Pretreat the workpiece, and analyze its specifications, accessory dimensions, usage environment, and wear mechanism;

[0030] Step S2: Perform flaw detection on the workpiece, including penetrant flaw detection and ultrasonic flaw detection, to ensure the integrity of the base material performance of the workpiece;

[0031] Step S3: Clean the surface of the workpiece, remove the oxide layer, and increase the surface roughness through sandblasting until the surface roughness range of the workpiece is 4.0 - 4.2 μm;

[0032] Step S4: Spray the workpiece using a plasma flame spraying system and bismuth alloy powder, so that the bismuth alloy powder adheres uniformly to the surface of the workpiece to form a bismuth alloy coating. The thickness of the bismuth alloy coating is greater than 0.35 mm, and the bonding strength reaches 40 MPa;

[0033] Step S5: Seal the sprayed coating until the porosity of the sprayed coating is reduced to within 0.5%.

[0034] Step S1 in this embodiment is used to achieve pretreatment. Analyses are carried out respectively according to the specifications, sizes, usage environments, and wear mechanisms of each accessory. Mainly, according to the usage environment and working conditions of the product, subjective analyses are conducted by combining different usage parameters with basic drilling knowledge. Currently, the mainstream specifications are the accessories corresponding to tools of two sizes, 172 mm and 121 mm, and the corresponding accessory sizes are 48 mm and 35 mm respectively. The usage environment mainly includes working conditions that require high-speed jet drilling with large displacement (above 55 L / S), high pump pressure (above 35 MPa), and high mud density (above 2.1 g / cm 3 ). The main wear mechanism is the erosion loss of the outer surface of the instrument caused by the scouring of the drilling fluid with large displacement.

[0035] Therefore, in step S1 of this embodiment, the usage environment of the workpiece includes at least one of displacement, pump pressure, and mud density to correspond to the drilling working conditions of the workpiece, and the erosion loss of the outer surface of the instrument caused by the scouring of the drilling fluid is associated as the wear mechanism.

[0036] Step S2 in this embodiment is used to detect flaws in the workpiece, including dye penetrant inspection and ultrasonic inspection, to determine that the performance of the base material of the workpiece is intact without scars such as cracks, depressions, and defects.

[0037] Step S2 in this embodiment preferably includes the following sub-steps:

[0038] Step S201, clean and dry the workpiece, and after the drying treatment, permeate it with a penetrant and observe it with a developer;

[0039] Step S202, emit ultrasonic signals from the probe to the workpiece, recover the wave amplitude through the detector, and analyze the recovered wave amplitude to determine whether there are defects or cracks in the workpiece.

[0040] Among them, dye penetrant inspection is one of the methods of non-destructive testing, mainly used to detect surface damages such as cracks that cannot be identified by the naked eye. Combining with this embodiment, it is mainly used to check the defects of dense metal materials, including cracks, pores, etc.; the main process is: cleaning the workpiece, permeating it with a penetrant, and observing it with a developer.

[0041] Ultrasonic inspection is a detection method that uses an ultrasonic detection instrument to conduct acoustic wave reflection on the workpiece. The detection methods include the direct contact method and longitudinal wave detection. For the detection of defects and cracks in the instrument body, connect the ultrasonic detector to the probe, the probe emits ultrasonic signals to the workpiece, the detector recovers the wave amplitude, and whether there are defects and cracks can be determined through the analysis of the wave amplitude.

[0042] More preferably, in step S202 of this embodiment, the high-frequency ultrasonic signal and the low-frequency ultrasonic signal are combined to detect surface and internal defects of the workpiece respectively, and flaw detection is realized through multi-frequency ultrasonic waves, which can effectively improve the detection accuracy.

[0043] Step S3 of this embodiment is used to realize surface deoxidized layer cleaning and sandblasting treatment.

[0044] Among them, for surface deoxidized layer cleaning, when the surface has general floating rust, it can be first brushed back and forth with a wire brush, and then polished with coarse sandpaper to produce a new bright surface; if the surface rust is relatively serious, the rust can be first shoveled off with a spatula, then cleaned with a wire brush, and then polished with sandpaper until it is bright; if there is large-area rust, electric rust removal tools such as grinders and pneumatic grinders can be used to remove rust first, and then tools such as wire brushes, files and sandpaper are used to remove the remaining rust and sundries. And sandblasting treatment is used to increase the roughness to 4.0 - 4.2 to increase the coating adhesion.

[0045] Therefore, in step S3 of this embodiment, the surface of the workpiece is first cleaned, including removing the oxidized layer by one or more of shoveling off the rust with a spatula, cleaning with a wire brush, and polishing with coarse sandpaper; then, the surface roughness is increased by sandblasting treatment, and the surface roughness is detected in real time during the sandblasting treatment until the surface roughness range of the workpiece is 4.0 - 4.2μm, then the sandblasting treatment is stopped and the process jumps to step S4.

[0046] Step S4 of this embodiment is used to realize spraying treatment. In this step, the spraying equipment preferably adopts a plasma flame spraying system equipment, and the raw material adopts a composite powder of bismuth alloy powder, which meets the non-magnetic working condition (magnetic permeability limf(x) = 0). In step S4, the bismuth alloy powder includes metallic bismuth powder and auxiliary metal powder, and the auxiliary metal powder includes any one or several of metallic tin powder, metallic lead powder, metallic antimony powder and metallic indium powder. By mixing these various metal powders, different proportions and dosages can be determined according to different workpieces. And the composition and proportion (i.e., proportion and dosage) of various metal powders are determined according to different working environments. The bismuth alloy powder adheres evenly to the surface of the workpiece, the coating thickness > 0.35mm, and the bonding strength reaches 40MPa.

[0047] In step S4 of this embodiment, a spraying parameter table is preset, and for each specification model, fitting size, use environment and wear mechanism of the workpiece, the corresponding bismuth alloy powder composition and proportion are preset; that is, through preliminary experiments and tests, for various specification models, fitting sizes, use environments and wear mechanisms of the workpiece, the composition and proportion of various metal powders required by each can be determined in advance. During the actual spraying process, the composition and proportion of the bismuth alloy powder can be determined according to the current use environment.

[0048] In this embodiment, step S5 penetrates and seals the sprayed coating (i.e., the bismuth alloy coating) by using a self-developed sealing process, effectively reducing the porosity of the sprayed coating from 2% to less than 0.5%, so as to minimize the proportion of pores in the sprayed coating and achieve the effect of hole sealing. The sprayed coating refers to the bismuth alloy coating.

[0049] Specifically, step S5 in this embodiment preferably includes the following sub-steps:

[0050] Step S501: Attach a sealant to the processing part of the workpiece, place the workpiece with the attached sealant in a pressurized container, input compressed air for pressurization treatment, pressurize to 1.5 MPa, and maintain it in a pressurized environment of 1.5 ± 0.1 MPa for more than 2 hours;

[0051] Step S302: Heat the workpiece in an electric control manner to 95 - 100 °C, and maintain it in a heating environment of 95 - 100 °C for 1.5 - 2 hours.

[0052] It should be noted that the sealing process of step S5 achieved through the above two sub-steps can make the existing sealant better integrate into the sprayed coating (i.e., the bismuth alloy coating), effectively reduce pores and porosity in the pressurization and heating treatment environment, and further improve the wear resistance of the coating.

[0053] More preferably, in step S501 of this embodiment, the pressurization treatment is up to 1.5 ± 0.1 MPa and maintained for 2.3 - 2.5 hours to more effectively make the sealant well integrate into the bismuth alloy coating; on this basis, in step S502, during the maintenance process of heating to 95 - 100 °C (i.e., the heating environment), continue the pressurization treatment. At this time, it is not necessary to pressurize to 1.5 MPa again, but pressurize to 1.2 ± 0.05 MPa and maintain it, which can well ensure that the porosity of the sprayed coating after sealing is reduced from the original 2% to less than 0.5%. It still meets the actual application requirements of downhole measurement instrument accessories for directional instrument accessories such as those used in oil drilling while-drilling measurement instruments after more than 5000 hours of acetic acid salt spray test, and the surface impact resistance is greater than or equal to 3.0 J, and the surface hardness is greater than 1000 HV.

[0054] In summary, in this embodiment, the workpiece is first pre-treated to analyze its specifications, fitting dimensions, usage environment, and wear mechanism, so as to conduct targeted analysis in combination with drilling parameters according to the usage environment and working conditions of various workpieces; then, the workpiece is subjected to flaw detection, including penetrant inspection and ultrasonic flaw detection, to ensure the integrity of the base material performance of the workpiece; the surface of the workpiece is cleaned to remove the oxide layer, and the surface roughness is increased by sandblasting until the surface roughness range of the workpiece is 4.0 - 4.2 μm, so as to increase the coating adhesion for subsequent spraying treatment; then, the workpiece is sprayed with a plasma flame spraying system and bismuth alloy powder, so that the bismuth alloy powder is evenly attached to the surface of the workpiece to form a bismuth alloy coating, the thickness of the bismuth alloy coating is greater than 0.35 mm, and the bonding strength reaches 40 MPa, so as to increase the surface impact resistance and hardness of the coating; finally, the sprayed coating is sealed until the porosity of the sprayed coating is reduced to less than 0.5%, so as to well meet the actual application requirements of this kind of directional instrument fitting for the accessories of the measurement-while-drilling instrument in oil drilling.

[0055] To verify the performance of the erosion-resistant strengthening coating method for the accessories of the measurement-while-drilling instrument in oil drilling, including indicators such as coating thickness, bonding strength, impact resistance, hardness, corrosion resistance, porosity, and non-magnetism.

[0056] Table 1 Test Samples

[0057]

[0058] Table 2 Test Items and Data

[0059]

[0060]

[0061] From the test results, it can be seen that this embodiment can achieve the following technical effects: 1. The thickness of the composite coating is greater than 0.35 mm; 2. The coating bonding strength is greater than 40 MPa; 3. The surface impact resistance is greater than or equal to 3.0 J; 4. The surface hardness is greater than 1000 HV; 5. The acetate salt spray test is greater than 5000 hours; 6. The porosity before sealing is about 2%; 7. The porosity after sealing is less than 0.5%; 8. It meets the non-magnetic working conditions.

[0062] Therefore, this embodiment well provides a new erosion-resistant strengthening coating method for the accessories of the measurement-while-drilling instrument in oil drilling, effectively improving the use efficiency of the instrument accessories, saving the procurement and maintenance costs, and extending its service life.

[0063] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for an erosion-resistant strengthening coating of accessories for a measurement-while-drilling instrument in oil drilling, characterized in that, It includes the following steps: Step S1, preprocess the workpiece, and analyze its specification model, fitting size, usage environment, and wear mechanism; Step S2, perform flaw detection on the workpiece, including penetrant inspection and ultrasonic flaw detection, to ensure the integrity of the base material performance of the workpiece; Step S3, clean the surface of the workpiece, remove the oxide layer, and increase the surface roughness through sandblasting until the surface roughness of the workpiece ranges from 4.0 to 4.2 μm; Step S4, spray the workpiece using a plasma flame spraying system and bismuth alloy powder, so that the bismuth alloy powder is evenly attached to the surface of the workpiece to form a bismuth alloy coating, the thickness of the bismuth alloy coating is greater than 0.35 mm, and the bonding strength reaches 40 MPa; Step S5, perform a sealing treatment on the sprayed coating until the porosity of the sprayed coating is reduced to less than 0.5%.

2. The erosion-resistant strengthening coating method for accessories of oil drilling measurement-while-drilling instruments according to claim 1, characterized in that, In the said Step S1, the usage environment of the workpiece includes at least one of displacement, pump pressure, and mud density, corresponding to the drilling conditions of the workpiece, and the erosion loss on the outer surface of the instrument caused by the flushing of the drilling fluid is associated as the wear mechanism.

3. The erosion-resistant and strengthening coating method for accessories of measurement-while-drilling instruments in oil drilling according to claim 1, wherein The said Step S5 includes the following sub-steps: Step S501, attach a sealant to the processing part of the workpiece, place the workpiece with the attached sealant in a pressurized container, input compressed air for pressurization treatment, pressurize to 1.5 MPa, and maintain for more than 2 hours; Step S302, perform a heating treatment on the workpiece in an electric control manner, heat up to 95 - 100 °C, and maintain for 1.5 - 2 hours.

4. The erosion-resistant and strengthening coating method for accessories of the measurement-while-drilling instrument for oil drilling according to claim 3, wherein, In the said Step S501, pressurize to 1.5 ± 0.1 MPa and maintain for 2.3 - 2.5 hours.

5. The erosion-resistant strengthening coating method for accessories of the measurement-while-drilling instrument for oil drilling according to claim 3, characterized in that, In the said Step S502, during the maintenance process of heating up to 95 - 100 °C, continue the pressurization treatment, and pressurize to 1.2 ± 0.05 MPa.

6. The erosion-resistant and strengthening coating method for accessories of oil drilling measurement-while-drilling instruments according to any one of claims 1 to 5, characterized in that, The said Step S2 includes the following sub-steps: Step S201, clean and dry the workpiece, and after the drying treatment, penetrate it with a penetrant and observe it with a developer; Step S202, emit ultrasonic signals from the probe to the workpiece, recover the wave amplitude through a detector, and analyze the recovered wave amplitude to determine whether there are defects or cracks in the workpiece.

7. The erosion-resistant and strengthening coating method for accessories of measurement-while-drilling instruments in oil drilling according to claim 6, wherein, In the said Step S202, combine high-frequency ultrasonic signals and low-frequency ultrasonic signals to detect surface and internal defects of the workpiece respectively.

8. The erosion-resistant strengthening coating method for accessories of measurement-while-drilling instruments in oil drilling according to any one of claims 1 to 5, characterized in that, In the said Step S3, first clean the surface of the workpiece, including removing the oxide layer by one or more of scraping off rust with a spatula, cleaning with a wire brush, and grinding with coarse gauze; then, increase the surface roughness through sandblasting, and perform real-time detection of the surface roughness during the sandblasting process. When the surface roughness of the workpiece ranges from 4.0 to 4.2 μm, stop the sandblasting treatment and jump to Step S4.

9. The erosion-resistant strengthening coating method for accessories of a measurement-while-drilling instrument for oil drilling according to any one of claims 1 to 5, characterized in that, In the said Step S4, the bismuth alloy powder includes metallic bismuth powder and auxiliary metal powder, and the auxiliary metal powder includes any one or several of metallic tin powder, metallic lead powder, metallic antimony powder, and metallic indium powder.

10. The erosion-resistant and strengthening coating method for accessories of the measurement-while-drilling instrument in oil drilling according to any one of claims 1 to 5, characterized in that, In the step S4, a spraying parameter table is preset, and for each specification model, fitting size, use environment, and wear mechanism of the workpiece, the corresponding composition and proportion of the bismuth alloy powder are preset; during the actual spraying process, the composition and proportion of the bismuth alloy powder are determined according to the current use environment.

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