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Ni60 self-fluxing alloy powder
Release time:
2019-12-12 16:45
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Ni60 self-fluxing alloy powder
Ni60 self-fluxing alloy powder is one of the most important grades in the nickel-based self-fluxing alloy powder series. Its distinguishing feature is its high iron content (≤15%), whereas similar foreign-grade powders have lower iron content (≤5%). Table 1 lists a comparison of the Ni60 alloy composition (mass fraction) with that of comparable foreign alloys.
Table 1: Comparison of the Chemical Composition of Ni60 Alloy
The hardness of the Ni60 powder spray-welding layer is around HRC60, comparable to that of surface-hardening treatments such as carburizing, nitriding, boriding, chrome plating, and certain surfacing alloys. It also boasts excellent comprehensive performance in terms of wear resistance, corrosion resistance, and resistance to high-temperature oxidation. As a result, it has been widely used for the repair and protection of wear-prone components in fields including metallurgy, machinery, mining, petroleum, chemical industry, light industry, and automotive industries, significantly extending service life by factors ranging from several to dozens of times and yielding remarkable economic and social benefits.
II. Ni60 Powder performance and the performance of the spray-welded layer
2.1 Appearance
The morphology of Ni60 powder was examined using a scanning electron microscope (see Figure 1), revealing that the prepared powder exhibits good sphericity and a smooth surface. During spray welding, the powder does not clog the nozzle orifices, making it easy to control the powder feed rate and suitable for automated spray-welding operations.
2.2 Developing Organization
Analysis and observation using an X-ray diffractometer in conjunction with an optical metallographic microscope revealed that the cross-sectional microstructure of Ni60 powder particles consists of a gray matrix composed of an Ni-Si solid solution, with uniformly dispersed Ni phases. 3 Phase B. Observation and analysis of the microstructure of the Ni60 spray-welded layer reveal that the matrix of the spray-welded layer is white.
Blocky silicon-containing nickel-chromium solid-solution phase; the hard phase is composed of fine, black, dotted particles of (Cr, Fe). 23 C 6 Gray blocky Ni 3 It consists of B and fine, white, blocky CrB. The microstructure of the 12496 spray-welded layer is similar to that of Ni60; however, due to its lower iron content, there are some differences in the size and number of the white blocks.
2.3 Physical Properties
The density, melting point, loose packing density, tapped density, flowability, and oxygen content of Ni60 powder, when compared with those of Grade 12496, show that the two sets of data are similar.
The oxygen content in powder is one of the important indicators for assessing powder quality. Powders with high oxygen content tend to produce more slag in the spray-welding layer and exhibit poor surface quality; therefore, powders are required to have low oxygen levels. Generally, the [O] content in alloy liquid is very low—analytical results show it ranges from 0.0007% to 0.0020%. Thus, it can be concluded that the oxygen content in the powder is mainly the result of secondary oxidation during the atomization of the alloy liquid. If the alloy liquid contains elements with a strong affinity for oxygen, the oxygen content will be even higher. Aluminum is such an element; its oxygen-absorbing capacity exceeds that of boron and silicon. Figure 2 illustrates the relationship between the oxygen content in the powder and the residual aluminum content.
2.4 Particle Size Distribution
The particle size distribution of Ni 60 powder, 10009 powder, and 12496 powder was tested using the particle size analysis method specified in GBl430—79. The comparison results are shown in Figure 3. As can be seen from the figure, the particle size distribution of the developed alloy powders is comparable to that of the imported 12496 powder.
2.5 Thermal Expansion Coefficient of the Powder
The measured thermal expansion coefficient of Ni60 is close to that of the 12496 alloy (see Figure 4). Both alloys exhibit relatively low thermal expansion coefficients, and their thermal expansion coefficients increase as the temperature rises. Therefore, it is necessary and important to preheat the workpiece before spray welding. Preheating treatment can bring the thermal expansion coefficients of the spray-welded alloy layer and the workpiece into closer alignment, thereby preventing cracking and spalling of the spray-welded layer.
2.6 Thermal Conductivity
The thermal conductivity of the alloy is also one of the key factors underlying the development of powder spray-welding processes. The thermal conductivity of the alloy was determined using a T2-type laser pulse thermal conductivity meter. The measured thermal conductivity of Ni60 is close to that of the 12496 alloy (see Figure 5), and both alloys exhibit relatively low thermal conductivities that increase with rising temperature. Therefore, it is evident that the cooling method employed after spray welding is crucial. The purpose of heat preservation is to slow down the temperature drop between the spray-welded layer and the substrate, thereby reducing the temperature gradient and preventing cracking and spalling of the spray-welded layer.
2.7 Hardness of the spray-welded layer
2.7.1 Room-Temperature Hardness
The hardness of the spray-welded layer was measured using an HR-150AT optical Rockwell hardness tester. Based on statistical analysis of test data from 20 batches of Ni60 specimens, the hardness of the weld layer with the upper limit composition was HRc62, the hardness with the middle limit composition was HRc59, and the hardness with the lower limit composition was HRc55. Under the same testing conditions, the hardness of the weld layer for 12,496 specimens was measured as HRc58. It is evident that there is no significant difference in hardness between these two sets of results.
2.7.2 High-Temperature Hardness of the Spray-Welding Layer
The high-temperature hardness was measured using the (Japanese) VH—5B vacuum high-temperature Vickers hardness tester. The high-temperature hardness values of the Ni60 and 12496 spray-welded layers are shown in Figure 6. As can be seen from Figure 6, the high-temperature hardness of the spray-welded layers made from the two alloy powders is at the same level.
2.8 Wear Resistance of the Spray-Welding Layer
2.8.1 Intermetallic Wear
Intermetallic wear was determined using the Sodertag rapid wear testing machine. During the test, loads of 5 kg, 10 kg, 15 kg, and 20 kg were applied at a rotational speed of 750 r/min. The specimens were cooled with 0.25% trisodium phosphate solution, and the wear volume was measured after 3,000 revolutions. The specimen dimensions were φ22 × 22 mm × 10 mm, with a weld layer thickness exceeding 1 mm. The reference materials were GCrl5 steel, quenched to a hardness of approximately HRC60, and No. 45 steel. The test results are shown in Figure 7. As can be seen from Figure 7, the wear resistance of the 12496 alloy and the Ni-based weld layer is essentially the same, both being more than four times higher than that of GCrl5 steel and No. 45 steel.
2.8.2 Abrasive Wear
The abrasive wear test was conducted using the Fargo rubber-wheel abrasive wear testing machine. The materials compared were cobalt-chromium-tungsten alloy, high-chromium cast iron, 35CrMoAl, and 16Mn steel. The test results showed that the wear loss of the Ni60 alloy was between one-third and one-forty-eighth of that of the comparison materials, demonstrating its outstanding resistance to abrasive wear.
2.9 High-Temperature Oxidation Resistance of the Spray-Welded Layer
The high-temperature oxidation resistance test was conducted in accordance with GB64-46 standard. The specimen dimensions were φ8 mm × 3 mm, with a surface finish of 1.6 μm. The test temperatures were 650℃, 750℃, and 850℃, and the oxidation duration was 200 hours. Weighing was performed once per hour, and the average value of two specimens was taken for each specification. The test results are shown in Figure 8. As can be seen from Figure 8, both the Ni60 and 12496 weld layers exhibit excellent oxidation resistance, with only minor differences between them. Under high-temperature conditions, the spray-welded layer of 12496 demonstrates slightly superior oxidation resistance.
III. Applications
Due to the excellent wear resistance, corrosion resistance, high-temperature oxidation resistance, and high hardness of Ni60 alloy powder, it is bound to find widespread applications in various industrial sectors. The following are some of the results achieved through the use of Ni60 alloy powder:
(1) The tuyere straight-blow pipe seats and nozzles of the blast furnace are subjected to high-temperature erosion at 1050–1100℃. By applying Ni60 spray welding for preliminary protection, the service life has been increased by more than four times compared to the original design.
(2) When the wire-drawing machine wheel for water tanks is made from bearing steel, its service life is only 2 to 3 weeks. However, after switching to a manufacturing process that involves spray-welding an Ni60 alloy layer onto the surface of No. 45 steel, the wheel’s service life increases by more than five times, and the surface quality of the steel wire is also significantly improved.
(3) The φ600mm hot-treated coiling roller, subjected to intense abrasion from the steel wire, has an extremely short service life. After being treated with a new solid-phase penetration process using Ni60 spray welding, its wear resistance is significantly improved, increasing its service life by more than 20 times compared to the original.
(4) The rolling mill conveyor roller (G roller), with Ni60 spray welding for surface strengthening and pre-protection, has a service life more than four times longer than the original.
(5) The forming roll for the φ180mm cold-formed steel production line, used for manufacturing “2010 screen window profiles,” after spray welding with Ni60, has increased its capacity from originally being able to roll only 7 tons of steel to being able to roll over 100 tons of steel.
(6) After adopting Ni60 spray-welded rolling guide devices for rolling mills, internal molds for cold-drawn steel tubes, and 90T shear blades, the service life of each component has increased by more than six times compared to the original.
In addition, Ni60 spray welding is also used for the repair and pre-protection of components such as rolling mill gears, idler gears, bearing housings, pump sleeves, fan blades, planer pressure plates, pump casings, plungers, pistons, agricultural machinery parts, and corrosion-resistant components, all of which have achieved excellent performance.
IV. Conclusion
(1) Ni60 powder is produced using inexpensive materials and a water atomization process, resulting in low costs, affordable prices, and excellent spray welding performance.
(2) The Ni60 spray-welded coating exhibits excellent comprehensive performance, including superior wear resistance, corrosion resistance, and oxidation resistance, while also maintaining a certain degree of machinability. It is used for component repair and pre-protection, significantly extending the service life of components by factors ranging from several to dozens of times.
(3) The Ni60 alloy powder developed boasts comprehensive performance that matches or even approaches the level of the renowned Swiss grade 12496, making it an exceptionally ideal hard powder material.
Relevant Information
The complete set of plasma-sprayed equipment has been shipped to the customer’s site in Thailand.
Core spraying equipment: SX-80 plasma spray main unit, with a 15,000℃ flame suitable for multiple materials including zirconia and silicon carbide; powder feeding accuracy of ±1%, and coating thickness tolerance ≤ ±5 μm. Environmental protection support system: Customized soundproof booth + pulse dust collector—effectively addressing spray noise pollution while achieving highly efficient dust recovery, compliant with Thai environmental standards. Automated equipment: 6-axis industrial robot + intelligent spray cart, enabling precise spraying of complex workpieces and automated loading/unloading, boosting production efficiency by 40%.
On-site engineers provide hands-on training, focusing on the core operations of plasma spraying equipment such as the SX-80. Sanxin has customized a complete solution for its customers, including an automated spraying robotic arm, a soundproof booth, and a dust removal system—ensuring both high spraying efficiency and compliance with environmental standards.
Guangzhou Sanxin Thermal Spraying Turntable Shipment
Guangzhou Sanxin Company manufactures single-station and multi-station thermal spray turntables, which can be paired with plasma equipment, supersonic equipment, and arc equipment. We offer rapid, customized production tailored to customer requirements and product dimensions. A thermal spray turntable is a high-precision rotary worktable specifically designed for thermal spraying processes—including flame spraying, plasma spraying, and arc spraying. By providing controllable rotational speed and exceptional stability, it ensures uniform coating thickness on the workpiece surface, thereby enhancing spraying efficiency and quality.
SX-80 plasma equipment is being used at a customer site in Russia.
SX-80 plasma equipment is being used at a customer site in Russia.
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