A method of making a mixed tungsten carbide particulate filled electrode

Abstract

The application provides a preparation method of a mixed tungsten carbide particle filled electrode, comprising the following steps: step S1, mixing an alloy binder phase, a WC powder and an organic binder, preparing an alloy tungsten carbide rod by using an extrusion process and drying; step S2, sintering the dried alloy WC rod; step S3, preparing spherical alloy WC balls by using a plasma rotating atomization device; step S4, mixing the alloy WC balls with multiangular coarse WC particles, filling the mixed WC particles into a thin-walled stainless steel pipe with an open end, filling the mixed WC particles into the thin-walled stainless steel pipe, closing the open end and obtaining the mixed tungsten carbide particle filled electrode. The mixed tungsten carbide particle filled electrode has the characteristics of uniform WC distribution and good welding process performance of the electrode; the hard alloy WC particles in the surfacing coating prepared by using the electrode are uniformly distributed, the nominal free path of the alloy binder phase is small, and the coating has excellent wear resistance.

Description

Technical Field

[0001] This invention relates to the field of surface technology, and more particularly to a method for preparing a welding electrode filled with mixed tungsten carbide particles. Background Technology

[0002] Currently, WC welding electrodes used for manual welding of high wear-resistant coatings are generally manufactured by filling thin-walled stainless steel with molten, broken, polygonal, irregularly shaped WC. Due to the poor fluidity of polygonal, irregularly shaped WC, when poured into stainless steel pipes with small diameters, uneven distribution of WC often occurs within the pipe. This leads to unstable welding processes and uneven distribution of WC in the weld layer. In addition, because the nominal free path of the alloy bond phase between the large polygonal, irregularly shaped WC particles is large, abrasive grains can easily cut off this alloy bond phase between the large WC particles. Thus, the protruding WC is easily subjected to lateral impact from abrasive grains. Although polygonal, irregularly shaped WC has high hardness, it is also brittle. Therefore, polygonal, irregularly shaped WC is prone to cracking and detachment when subjected to abrasive impacts, making it difficult to effectively utilize the excellent wear-resistant properties of the hard phase. Summary of the Invention

[0003] The purpose of this invention is to overcome and supplement the deficiencies in the existing technology, and to provide a method for preparing a welding electrode filled with mixed tungsten carbide particles, so that the hard phase is uniformly distributed in the WC-based coating welded by the welding electrode, the nominal free path of the alloy binder phase is small, and the weld layer has a uniform microstructure and excellent wear resistance.

[0004] The technical solution adopted in this invention is: A method for preparing a welding electrode filled with mixed tungsten carbide particles, comprising the following steps: Step S1. Mix the alloy binder phase, WC powder and organic binder by mass percentage, then prepare alloy tungsten carbide rods by extrusion and dry them; Step S2. The dried alloy WC rods are sintered and densified in a vacuum furnace; Step S3. The sintered alloy WC rods are processed into spherical alloy WC balls using a plasma rotary atomization device and then sieved to obtain alloy WC balls with different particle sizes. Step S4. Alloy WC spheres with a particle size distribution of 5~300µm are thoroughly mixed with polygonal coarse WC particles with a particle size distribution of 100~1000µm in a certain proportion. The mixed powder is then poured into a thin-walled stainless steel tube with one open end. Ultrasonic vibration is then used to assist filling so that the mixed WC particles uniformly fill the thin-walled stainless steel tube. The open end is then sealed to obtain a welding electrode filled with mixed tungsten carbide particles.

[0005] Preferably, in the method for preparing the welding electrode filled with mixed tungsten carbide particles, the mass ratio of the alloy binder phase, WC powder, and organic binder in step S1 is 6~29:70~93:1~3.

[0006] Preferably, in the method for preparing the welding electrode filled with mixed tungsten carbide particles, the alloy binder phase in step S1 is selected from one or more of Ni, Cr, Co, Mo, Cu, Mn, and Fe.

[0007] Preferably, in the method for preparing the welding electrode filled with mixed tungsten carbide particles, the organic binder in step S1 is selected from either PVA or paraffin wax.

[0008] Preferably, in the method for preparing the welding electrode filled with mixed tungsten carbide particles, the sintering densification process in step S2 specifically involves: heating to 350°C and holding for 1 hour, then heating to 1300°C and holding for 1.5 hours, and finally heating to 1430°C and holding for 1.5 hours.

[0009] Preferably, in the method for preparing the welding electrode filled with mixed tungsten carbide particles, the mass ratio of alloy WC spheres to polygonal coarse WC particles in step S4 is 5%~40%:60%-95%.

[0010] Preferably, in the method for preparing the welding electrode filled with mixed tungsten carbide particles, the alloy composition of the fine-particle spherical alloy WC in step S4 is one or more of Ni, Cr, Co, Mo, Cu, Mn, and Fe, and the alloy accounts for 6 to 29 wt% of the fine-particle spherical alloy WC.

[0011] Preferably, in the method for preparing the welding electrode filled with mixed tungsten carbide particles, the thin-walled steel pipe used for injecting the mixed tungsten carbide particles in step S4 has a diameter of 3~8mm, a wall thickness of 0.1~0.8mm, and is made of stainless steel grade 304, 316 or 310.

[0012] Advantages of this invention: The present invention discloses a method for preparing a welding electrode filled with mixed tungsten carbide particles. The method involves preparing alloy WC rods using a mixing and sintering method, followed by preparing spherical alloy WC using a plasma rotary atomization method. The prepared spherical alloy WC powder is then sieved, and a mixed powder consisting of spherical alloy WC with a particle size distribution of 5-200µm and coarse polygonal WC particles is poured into a stainless steel tube. Compared to traditional welding electrodes filled with large-particle polygonal WC, this welding electrode filled with mixed tungsten carbide particles exhibits uniform WC distribution and good welding processability. Furthermore, the hard alloy WC particles in the surfacing coating prepared using this electrode are uniformly distributed, the nominal free path of the alloy binder phase is small, and the coating exhibits good impact resistance and excellent wear resistance. Attached Figure Description

[0013] Figure 1 The morphology of the coating after abrasive wear using traditional coarse-particle tungsten carbide filler electrodes.

[0014] Figure 2 The morphology of the surfacing coating made with the mixed tungsten carbide filler electrode in Example 1 after abrasive wear.

[0015] Figure 3 The morphology of the coating material after abrasive wear using the mixed tungsten carbide filler electrode in Example 2.

[0016] Figure 4 The morphology of the surfacing coating made with the mixed tungsten carbide filler electrode in Example 3 after abrasive wear. Detailed Implementation

[0017] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0018] Example 1 A method for preparing a welding electrode filled with mixed tungsten carbide particles includes the following steps: Step S1. Mix the alloy binder phase Ni, WC powder and organic binder paraffin at a mass ratio of 10:87:3, then prepare alloy tungsten carbide rods by extrusion and dry them. Step S2. The dried WC-Ni rod is sintered and densified in a vacuum furnace. The sintering and densification process is as follows: the temperature is raised to 350℃ and held for 1 hour, then the temperature is raised to 1300℃ and held for 1.5 hours, and finally the temperature is raised to 1430℃ and held for 1.5 hours. Step S3. The sintered WC-Ni rod is used to prepare spherical alloy WC balls through a plasma rotary atomization device and then screened to obtain WC-Ni balls with different particle sizes. Step S4. Thoroughly mix WC-Ni spheres with a particle size distribution of 5-300µm and polygonal coarse WC particles with a particle size distribution of 100-1000µm at a ratio of 5%:95%. Pour the mixed powder into a thin-walled stainless steel tube with an open end. The tube has a diameter of 8mm, a wall thickness of 0.5mm, and is made of 304 stainless steel. Ultrasonic compaction is used to assist filling, ensuring the mixed WC particles uniformly fill the tube. The open end is then sealed, resulting in a welding electrode filled with mixed tungsten carbide particles. The coating prepared using this mixed WC particle-filled welding electrode exhibits 9.3 times higher wear resistance than coatings prepared using traditional coarse-particle WC-filled welding electrodes. Wear resistance is tested according to the standard test method of ASTM G105-20 wet sand / rubber wheel wear test. A weld overlay coating is prepared on the surface of a low-carbon steel plate using this mixed WC particle-filled welding electrode. After surface grinding of the weld overlay, it is then processed according to the "JBT" standard. The national standard 7705-1995, "Test Method for Loose Abrasive Wear - Rubber Wheel Method," applies abrasive wear testing to weld overlay coating samples. The morphology of the tested samples is shown in the attached figure. Figure 2 As shown.

[0019] Example 2 A method for preparing a welding electrode filled with mixed tungsten carbide particles includes the following steps: Step S1. Mix the alloy binder phase cobalt (Co), WC powder, and organic binder paraffin at a mass ratio of 6:92:2, then prepare WC-Co rods by extrusion and dry them; Step S2. The dried WC-Co rods are sintered and densified in a vacuum furnace. The sintering and densification process is as follows: the temperature is raised to 350℃ and held for 1 hour, then the temperature is raised to 1300℃ and held for 1.5 hours, and finally the temperature is raised to 1430℃ and held for 1.5 hours. Step S3. The sintered WC-Co rods are processed into spherical WC-Co balls using a plasma rotary atomization device and then sieved to obtain WC-Co balls with different particle sizes. Step S4. Thoroughly mix WC-Co spheres with a particle size distribution of 5-300 µm and polygonal coarse WC particles with a particle size distribution of 100-1000 µm at a ratio of 10%:90%. Pour the mixed powder into a thin-walled stainless steel tube with an open end. The tube has a diameter of 7 mm, a wall thickness of 0.6 mm, and is made of 316 stainless steel. Ultrasonic compaction is used to assist filling, ensuring the mixed WC particles uniformly fill the tube. The open end is then sealed, resulting in a welding electrode filled with mixed tungsten carbide particles. This mixed WC particle-filled welding electrode is used to prepare a weld overlay coating on the surface of a low-carbon steel plate. After surface grinding, the weld overlay sample is subjected to abrasive wear testing according to the national standard "JBT 7705-1995 Loose Abrasive Wear Test Method - Rubber Wheel Method". The morphology of the tested sample is shown in the attached figure. Figure 3 As shown.

[0020] Example 3 A method for preparing a welding electrode filled with mixed tungsten carbide particles includes the following steps: Step S1. Cobalt (Co) and chromium (Cr) alloy binder phases, WC powder, and paraffin organic binder are mixed in a mass ratio of 15:82:3. WC-CoCr rods are then prepared by extrusion and dried. The mass ratio of cobalt to chromium in the alloy binder phase is 2.5:1. Step S2. The dried WC-CoCr rods are sintered and densified in a vacuum furnace. The sintering and densification process is as follows: the temperature is raised to 350℃ and held for 1 hour, then the temperature is raised to 1300℃ and held for 1.5 hours, and finally the temperature is raised to 1430℃ and held for 1.5 hours. Step S3. The sintered alloy WC rod is used to prepare spherical WC-CoCr balls through a plasma rotary atomization device and then sieved to obtain WC-CoCr balls with different particle sizes. Step S4. Thoroughly mix WC-CoCr spheres with a particle size distribution of 5-300 µm and polygonal coarse WC particles with a particle size distribution of 100-1000 µm at a ratio of 40%:60%. Pour the mixed powder into a thin-walled stainless steel tube with an open end. The tube has a diameter of 6 mm, a wall thickness of 0.4 mm, and is made of 316 stainless steel. Ultrasonic compaction is used to assist filling, ensuring the mixed WC particles uniformly fill the tube. The open end is then sealed, resulting in a welding electrode filled with mixed tungsten carbide particles. The coating prepared using this mixed WC particle-filled welding electrode exhibits 13.1 times higher wear resistance than coatings prepared using traditional coarse-particle WC-filled welding electrodes. A weld overlay coating is prepared on the surface of a low-carbon steel plate using this mixed WC particle-filled welding electrode. After surface grinding, the weld overlay is then processed according to "JBT 7705-1995". The national standard "Rubber Wheel Method for Testing Loose Abrasive Wear" applies abrasive wear testing to weld overlay coating samples. The morphology of the tested samples is shown in the attached figure. Figure 4 As shown.

[0021] from Figures 1-4 The sample morphology diagram shows that the weld overlay prepared with a powder core electrode containing a mixture of spherical and polygonal WC particles has shallower and smoother wear marks and a more uniform distribution of WC particles than the coating prepared with only polygonal coarse WC particles after wear testing.

[0022] The present invention discloses a method for preparing a welding electrode filled with mixed tungsten carbide particles. The method involves preparing alloy WC rods using a mixing and sintering method, followed by preparing spherical alloy WC using a plasma rotary atomization method. The prepared spherical alloy WC powder is then sieved, and a mixed powder consisting of spherical alloy WC with a particle size distribution of 5-200µm and coarse polygonal WC particles is poured into a stainless steel tube. Compared to traditional welding electrodes filled with large-particle polygonal WC, this welding electrode filled with mixed tungsten carbide particles exhibits uniform WC distribution and good welding processability. Furthermore, the hard alloy WC particles in the surfacing coating prepared using this electrode are uniformly distributed, the nominal free path of the alloy binder phase is small, and the coating exhibits good impact resistance and excellent wear resistance.

[0023] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a welding electrode filled with mixed tungsten carbide particles, characterized in that: Includes the following steps: Step S1. Mix the alloy binder phase, WC powder and organic binder by mass percentage, then prepare alloy tungsten carbide rods by extrusion and dry them; Step S2. The dried alloy WC rods are sintered and densified in a vacuum furnace; Step S3. The sintered alloy WC rods are processed into spherical alloy WC balls using a plasma rotary atomization device and then sieved to obtain alloy WC balls with different particle sizes. Step S4. Alloy WC spheres with a particle size distribution of 5~300µm are thoroughly mixed with polygonal coarse WC particles with a particle size distribution of 100~1000µm in a certain proportion. The mixed powder is then poured into a thin-walled stainless steel tube with one open end. Ultrasonic vibration is then used to assist filling so that the mixed WC particles uniformly fill the thin-walled stainless steel tube. The open end is then sealed to obtain a welding electrode filled with mixed tungsten carbide particles. The sintering densification process in step S2 is as follows: heat to 350℃ and hold for 1 hour, then heat to 1300℃ and hold for 1.5 hours, and finally heat to 1430℃ and hold for 1.5 hours. In step S4, the mass ratio of alloy WC spheres to polygonal coarse-grained WC particles is 5%~40%: 60%-95%; In step S1, the mass ratio of the alloy binder phase, WC powder, and organic binder is 6~29:70~93:1~3.

2. The method for preparing the welding electrode filled with mixed tungsten carbide particles according to claim 1, characterized in that: In step S1, the alloy binder phase is selected from one or more of Ni, Cr, Co, Mo, Cu, Mn, and Fe.

3. The method for preparing the welding electrode filled with mixed tungsten carbide particles according to claim 1, characterized in that: In step S1, the organic binder is selected from either PVA or paraffin.

4. The method for preparing the welding electrode filled with mixed tungsten carbide particles according to claim 1, characterized in that: In step S4, the alloy composition of the fine-particle spherical alloy WC is one or more of Ni, Cr, Co, Mo, Cu, Mn, and Fe, and the alloy accounts for 6 to 29 wt% of the mass of the fine-particle spherical alloy WC.

5. The method for preparing the welding electrode filled with mixed tungsten carbide particles according to claim 1, characterized in that: In step S4, the thin-walled steel pipe used for injecting the mixed tungsten carbide particles has a diameter of 3-8 mm, a wall thickness of 0.1-0.8 mm, and is made of stainless steel grade 304, 316, or 310.

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