47 results about "Particle size ratio" patented technology

This invention provides a brazing filler metal, a brazing filler metal preparation method, and a rectifier brazing method. The brazing filler metal includes a first brazing filler metal and a second brazing filler metal. The brazing filler metal preparation method involves uniformly mixing high-temperature alloy powder and brazing binder at a mass ratio of 2:1 to 3:1 to form the first brazing filler metal; and uniformly mixing BNi2 powder and brazing binder at a mass ratio of 10:1 to 15:1 to form the second brazing filler metal. By specifying brazing filler metals with a specific particle size ratio and applying different types of brazing filler metals in different zones, defects such as incomplete welding and porosity that are difficult to control in large-gap welds during processing and assembly are solved, improving the welding quality of welds with both large and small gaps, thereby increasing the product qualification rate.

This invention provides a low-cost, bimodal particle size distribution titanium-based powder for additive manufacturing, titanium-based parts, and a method for preparing the same. The method utilizes two different medium particle sizes D... 50 Using near-spherical titanium-based powder as raw material, a near-spherical bimodal particle size distribution titanium-based powder with good uniformity is obtained by wet mixing of suspension and rotary degreasing in a furnace. Various near-spherical bimodal particle size distribution titanium-based powders can also be prepared. The difference between these powders lies in the different particle size ratios and mass ratios of the two raw material powders used. The bulk density and flowability of each bimodal powder are tested to determine the range of particle size ratios and mass ratios of the two powders in near-spherical bimodal particle size distribution powders with high bulk density and flowability. This guides the preparation of high-quality near-spherical bimodal particle size distribution titanium-based powders for additive manufacturing. Ultimately, additive manufacturing technology is used to prepare high-performance, low-cost titanium-based parts to meet the stringent performance requirements of titanium components in high-end fields such as aerospace.

The present application provides a kind of polyurethane foam of wide frequency range sound absorption.The polyurethane foam of wide frequency range sound absorption includes polyurethane matrix and the porous polyurethane microsphere of bimodal distribution of particle size dispersed therein, the porous polyurethane microsphere is prepared by incomplete reverse emulsification method, its particle size presents bimodal distribution, the particle size ratio of large particle size porous microsphere and small particle size porous microsphere is 2:1~10:1, and the total mass ratio of large particle size porous microsphere and small particle size porous microsphere is 0.5:1~4:1.The present application is dispersed by bimodal distribution of porous polyurethane microsphere in polyurethane foam material, so as to obtain the polyurethane foam sound absorption material of wide frequency range, and the method process is simple.

The invention discloses an armored sand-ceramsite bimodal proppant based on performance matching as well as a preparation method and application thereof, and relates to the technical field of oil and gas exploitation. The proppant comprises ceramsite and armored sand which are compounded according to the mass ratio of (20: 80)-(60: 40), the volume density ratio of the ceramsite to the armored sand is 0.9-1.1, the median particle size ratio of the ceramsite to the armored sand is 1.5-3.0, it can be ensured that the proppant is evenly and stably conveyed to a target crack, the ceramsite forms a bearing framework, gaps are filled with the armored sand, and a synergistic and stable composite supporting structure is constructed. According to the proppant, the four-in-one performance matching design of volume density, breakage rate, acid solubility and particle size is adopted, the obtained proppant is superior to a conventional proppant in breakage resistance, acid corrosion resistance and long-term flow guide performance, the preparation cost is low, the defects of performance mismatch, system failure and the like of the conventional proppant can be overcome, and the proppant has wide application prospects in hydraulic fracturing construction of oil and gas fields.

A thermally conductive material obtained by dispersing a filler in a matrix composed of a resin. The filler includes spherical particles composed of aluminum nitride and plate-like particles composed of boron nitride. The volume ratio of plate-like to spherical particles is, for example, 0.4 to 1.5. The particle diameter ratio of the plate-like to the spherical particles is, for example, 0.05 to 0.5. The volume percent of the filler to the thermally conductive material as a whole is, for example, 73 to 93 vol %. The thermally conductive material that satisfies such conditions can develop remarkably high thermal conductivity. The thermally conductive material can be produced through a preparation step of obtaining a mixture in which spherical particles, plate-like particles, and a resin are present in a mixed manner, and a molding step of forming the mixture into a molded body. The preparation step may be performed in multiple stages.

Provided is a silica that exhibits a high matting property when utilized as a matting agent for a paint, and can also suppress the occurrence of cloudiness. The silica has an aggregated structure in which primary particles are aggregated, has a particle diameter ratio R represented by the following equation (1) of from 4.3 to 5.2, has an absorbance of 0.6 or less for light having a wavelength of 700 nm as an aqueous dispersion having a concentration of 1.48 mass %, and has a particle density measured with a He pycnometer of 2.18 g / cm3 or more: Equation (1) R=LD50 / CD50 (in the equation (1), LD50 represents a volume-based 50% cumulative particle diameter (μm) of the silica measured based on a laser diffraction / scattering method, and CD50 represents a volume-based 50% cumulative particle diameter (μm) of the silica measured based on a Coulter counter method).

The invention relates to the technical field of binder spray forming manufacturing, and discloses a method for regulating and controlling the surface roughness of a binder spray forming initial blank. The method comprises the following steps: acquiring a particle size reference ratio of raw material powder, preparing an initial blank by adopting a binder spray forming process according to the ratio, measuring the surface roughness of the initial blank to obtain a measured value, and comparing the measured value with a target roughness threshold value. And when the measured value is larger than the target roughness threshold value, the particle size ratio of the raw material powder is adjusted through the calculation model. And repeating the steps of preparing the initial blank, measuring the surface roughness and comparing until the measured value of the surface roughness is less than or equal to the target roughness threshold value. According to the method, accurate regulation and control of the surface roughness of the initial blank are achieved, diversified requirements of different products for the surface quality can be met, meanwhile, the method has the advantages of being efficient, low in cost and the like, and powerful support is provided for wide application of the binder spray forming technology in the manufacturing industry.

The invention discloses an automatic preparation method of high-permeability stratum shield slurry based on a deep learning model, and belongs to the technical field of high-permeability stratum shield slurry, and the method comprises the following steps: S1, designing slurry parameters by adopting an orthogonal design method, and selecting three factors of effective particle size, specific gravity and viscosity of slurry for research; the effective particle size of the slurry is prepared from pure bentonite slurry with the swelling-water ratio of 1: 12 and particle materials with different particle sizes; s2, carrying out penetration test on the prepared slurry sample in stratums with different permeability coefficients, and recording the change condition of the water filtering amount along with time, the type of a formed mud film and the thickness of the mud film; by establishing the quantitative evaluation index based on the deep learning model, the mud film performance can be accurately and objectively evaluated, and a scientific basis is provided for mud preparation. And in combination with quantitative evaluation indexes and a deep learning model, automatic optimization of the slurry formula is realized, the slurry preparation efficiency is improved, and the labor cost is reduced.

The invention discloses a pH response microcapsule dental floss and a preparation and use method thereof, and belongs to the technical field of oral care. The dental floss comprises a matrix and a color developing coating, the coating contains pH response microcapsules, the average particle size is 5-20 microns, the single-layer wall thickness is 0.5-2.0 microns, and the ratio of the wall thickness to the particle size is 0.03-0.3; the core material is a pH color-changing dye conforming to the GB / T 16886.10 standard, develops color in a plaque acid environment with the pH being less than or equal to 5.5, and automatically fades color in a neutral environment with the pH being greater than or equal to 6.8; and the wall material is a biocompatible polymer. The microcapsule is stable in saliva, is only broken and released under the friction shearing force of the dental floss, realizes the specific color development of the plaque, and disappears and is not stained after being washed with clear water. The preparation method comprises the following steps: preparing microcapsules by a complex coacervation method, preparing a coating solution, dipping and coating, and drying and sub-packaging. The dental floss is stable in storage and controllable in use, has cleaning, bacterial plaque visual detection and antibacterial functions, and remarkably improves user compliance.

To produce sintered ore having higher quality by using a mixed dry distilled material obtained by mixing iron ore with biomass and dry distilling the mixture.SOLUTION: A particle size adjustment step of adjusting the particle size of the biomass and the iron ore to a predetermined particle size, a carbonization step of carbonizing a mixture of the biomass and the iron ore having the adjusted particle size to produce a mixed carbonized product which is a mixture of a biomass carbide and a reduced ore, and a sintering step of producing sintered ore using the mixed carbonized product, wherein the predetermined particle size of the biomass is a top size of 3 mm or more and 7 mm or less, and the predetermined particle size of the iron ore is a top size of 7 mm or more and 10 mm or less, wherein a particle diameter ratio of a top size is 0.3 or more, a mass ratio of the biomass and the iron ore in the mixture is 0.2 or more, a dry distillation temperature in the dry distillation step is 700 °C or more and 900 °C or less, and a reduction rate of the reduced ore produced in the dry distillation step based on hematite is 70% or less.SELECTED DRAWING: Figure 1

The invention discloses a reactor for a sodium ion positive electrode material with high thermal shock resistance and a preparation method, and belongs to the technical field of reactors, the reactor comprises the following raw materials by weight: 20-30% of cordierite, 2-10% of talcum powder, 20-22% of mullite, 18-20% of tabular corundum, 12-18% of activated alumina, 4-8% of molybdenum trioxide, 5-6% of Guangxi white mud, 3-10% of an alumina silicate fiber fabric, and 4-8% of a binder; the binding agent is an aluminum dihydrogen phosphate solution with the concentration of 60%, and the aluminum silicate fiber fabric is subjected to high-temperature cracking treatment. According to the invention, by regulating and controlling the particle size ratio of cordierite to mullite, a compact network skeleton structure is formed in a reactor matrix, the stacking density and strength are optimized, the thermal stress is effectively dispersed, and cracks and spalling caused by temperature shock in a high-temperature repeated use process are reduced, so that the thermal shock stability of the reactor is improved.

The present application relates to aggregate gradation design method, asphalt mixture design method and pavement structure, comprising the following steps: sequentially determining the optimum dosage of each aggregate, the dosage determination method of adjacent two aggregates is: determining the average particle size ratio of fine aggregate and coarse aggregate in adjacent two aggregates; when the average particle size ratio is not greater than the set value, the first void index under a plurality of different coarse aggregate volume contents is measured, the boundary effect model is determined according to the first void index, the second void index when the coarse aggregate volume content is 100% is measured, the non-interference effect model is determined according to the second void index, and the optimum coarse aggregate dosage is determined according to the boundary effect model and the non-interference effect model; when the average particle size ratio is greater than the set value, the CBR value under a plurality of different coarse aggregate contents is measured, and the coarse aggregate volume content corresponding to the maximum CBR value is taken as the optimum coarse aggregate dosage, the aggregate gradation obtained by the design method satisfies the mineral material gap rate requirement.

The application discloses a preparation method of high-thermal-conductivity diamond composite material, and further discloses the obtained high-thermal-conductivity diamond composite material.The preparation method comprises the following steps: S1, putting transition diamond micro powder and a catalyst into a three-dimensional mixer to obtain first powder raw materials; S2, putting etched diamond particles and high-viscosity liquid into the three-dimensional mixer to obtain second powder raw materials; S3, putting the two kinds of powder raw materials into the three-dimensional mixer to mix and obtain third powder raw materials; S4, loading the third powder raw materials into a molybdenum material cup to form an assembly; S5, performing sintering reduction treatment on the assembly; and S6, putting the assembly after reduction into a six-surface press to synthesize the high-thermal-conductivity diamond composite material.The high-thermal-conductivity diamond composite material is prepared by the preparation method of the high-thermal-conductivity diamond composite material provided by the application, under the action of high temperature, high pressure and catalyst, and by optimizing the diamond particle size ratio, a good thermal conduction path is formed between the diamonds, and the diamond composite material with high thermal conductivity is prepared.

The application discloses a control method of a grinding machine group. The method comprises the following steps: acquiring a particle size ratio of target ore materials output from the second outlet of the cyclone group, the particle size of the target ore materials being less than or equal to a preset particle size threshold, the particle size ratio being a ratio between a content of the target ore materials and a content of total ore materials output from the second outlet; and if the particle size ratio is not in a preset particle size ratio range, adjusting a water adding rate of the first pump pulp tank until the particle size ratio is in the particle size ratio range, wherein the water adding rate is positively correlated with the particle size ratio. The classification accuracy of the cyclone group can be improved by the application.

The invention belongs to the technical field of photocuring 3D printing materials, and particularly relates to high-toughness and high-entropy ceramic photocuring slurry and a preparation method thereof.The preparation method comprises the steps that perfluoropolyether and nano zeolite powder are stirred and mixed for 1-3 hours at the temperature of 90-110 DEG C, and a first mixture is obtained; and adding polytetrafluoroethylene powder with a specific particle size ratio into the first mixture, continuously stirring and mixing at 200-220 DEG C for 1-3 hours, and cooling to obtain a second mixture, namely the anti-settling reinforcing agent, high-entropy ceramic powder is formed; compounding the slurry: adding a surface modifier, a photoinitiator and a toughness-enhanced nanophase into the anti-sedimentation enhancer obtained in the step 1, mixing, and ball-milling for 8-16 hours to obtain the high-toughness and high-entropy ceramic photocuring slurry, forming a stable three-dimensional network structure in the slurry, and preparing the high-toughness and high-entropy ceramic photocuring slurry by utilizing a steric hindrance effect and a lubricating effect. The sedimentation tendency of the high-density, multi-component and high-entropy ceramic powder is greatly inhibited, and the slurry does not cake after standing for 30 days.

The invention provides a high-specific-gravity high-toughness tungsten-nickel-copper alloy material and a preparation method thereof. The material comprises the following components in percentage by mass: 6-15% of nickel (Ni); copper (Cu): 2-5%; the manganese (Mn) accounts for 2-5%, and the balance is tungsten and inevitable impurities. The preparation method comprises the following steps: preparing materials (pure tungsten, pure nickel, pure copper and pure manganese powder), mixing the powder, pressing, sintering, and carrying out recrystallization annealing heat treatment. By adding the strengthening element manganese, combining the gradient particle size ratio and enhancing interface bonding, the high specific gravity and high strength of the material are kept, meanwhile, excellent toughness can be kept, and the material is suitable for aerospace gyroscope rotors and balance weight parts, electronic industry precise instrument parts, medical instrument ray shielding materials and national defense military industry kinetic energy armor-piercing weapon parts.

To provide a β-type silicon nitride powder that can easily produce sintered bodies with high dielectric breakdown voltage. [Solution] A silicon nitride powder having a β conversion rate of 80% or more, and in a volume-based particle size distribution curve measured by laser diffraction scattering, where D10 is the cumulative 10% particle size, D99 is the cumulative 99% particle size, and Dp is the particle size with the highest frequency, the ratio (D99-Dp) / (Dp-D10) is between 10 and 50.

The application provides a method, device and equipment for the coordinated control of channel scouring and evolution, and a storage medium. The method comprises the following steps: first, calculating a correlation coefficient according to a sediment transport potential field and a water depth change, and entering the next step if the verification fails; then, calculating a grouped and ungrouped sediment transport rate according to a real-time particle size distribution, and determining that the gradation is abnormal if the deviation is large. At the same time, the spatial graph convolution topography weight is corrected based on the maximum particle size ratio, the modified eddy viscosity coefficient is determined, the weight coefficient of the bed load is updated, and finally, the multi-physical field coupling model is updated by using the coefficients, so that the prediction accuracy of the channel scouring is improved.

This invention relates to a wet oxidation catalyst, its preparation method, and its application. The catalyst comprises a support and a metal oxide active component, wherein the metal oxide comprises Mo, Fe, and Co, and the relative particle size ratio of the oxidized crystal phases of the catalyst (Co...) is... 0.7 Fe 0.3 The ratio of (MoO4) / MoO3 is greater than or equal to 3.50. When using the catalyst of this invention to treat organic wastewater, the COD removal rate is high.

The application discloses an anti-freezing and thawing high-mixing-content bundle basalt fiber reinforced concrete and belongs to the technical field of concrete processing. The application is used for solving the technical problems of poor anti-freezing performance of the prior art concrete and further improvement of the mixing content of the basalt fiber in the concrete, and the anti-freezing and thawing high-mixing-content bundle basalt fiber reinforced concrete comprises the following components in parts by weight: coarse aggregate 70-78 parts, fine aggregate 30-35 parts, composite cement 25-30 parts, additive 0.2-0.3 parts, bundle reinforcing fiber 0.8-1.2 parts and water 15-20 parts. The application greatly improves the mixing content of the basalt fiber in the concrete by reinforcing and modifying the basalt fiber, and effectively enhances the mechanical properties and the anti-freezing and thawing performance of the concrete test piece by optimizing the particle size ratio of the coarse aggregate and the composite cement and the mutual cooperation of the bundle reinforcing fiber.

The invention provides an automatic control method for a mobile crusher, which comprises the following steps: acquiring the large particle size ratio, the medium particle size ratio, the small particle size ratio, the current roller spacing and the current feeding flow of a to-be-crushed material of the mobile crusher in real time, and identifying the surface adhesion coefficient of the material according to the water content of the material, extracting a distribution span value reflecting the difference between the agglomerating degree and the discrete particle span; according to the comparison result of the distribution span value and the crushing range threshold value of the mobile crusher, the risk level of mutual extrusion and blockage of the materials in the crushing channel is evaluated, and the high-risk clamping stagnation state when the distribution span value exceeds the crushing range threshold value is identified; the feeding flow is reduced according to the high-risk clamping stagnation state and the water content of the materials, the large-particle-size proportion, the medium-particle-size proportion and the small-particle-size proportion after the feeding flow is adjusted are collected, and the change track of the agglomeration degree and the change direction of the distribution span value are recognized.

A high-brightness fluoride phosphor is provided. The fluoride phosphor has the following composition: containing element M, at least one selected from alkali metals and ammonium ions, manganese, and fluorine atoms. Element M contains at least one selected from Group 4, Group 13, and Group 14 elements. When the total molar number of the alkali metal and ammonium ions is 2, the molar number of manganese is greater than 0 and less than 0.2, the total molar number of element M is greater than 0.8 and less than 1, the molar number of fluorine atoms is greater than 5 and less than 7, and the particle size ratio (Da / Dm) of the average particle size Da determined by the Fisher particle size distribution method to the volume median particle size Dm determined by laser diffraction particle size distribution method is greater than 0.85.

The invention discloses a black color master batch as well as a preparation method and application thereof. The black color master batch composition comprises the following components in parts by mass: 50-85 parts of a liquid crystal polymer; 15 to 40 parts of carbon black; 0.1 to 1 part of nano silicon dioxide; the average primary particle size ratio of the carbon black to the nano silicon dioxide is (3-8): 1. In the black color master batch composition, the nano silicon dioxide can improve the system viscosity and promote shear force transmission, and when the average primary particle size of the nano silicon dioxide is smaller than that of the carbon black, the nano silicon dioxide can be effectively dispersed and adsorbed on the surface of the carbon black to form a three-dimensional network structure and reduce the cohesion of the carbon black, so that the dispersity of the carbon black is improved; the size of the carbon black aggregate is reduced, and the number of the carbon black aggregate is reduced, so that a conductive path is formed in the matrix resin, and the resistivity is reduced; meanwhile, the high-temperature resistance is also suitable for a resin material system needing high-temperature processing.

Preparation of a silicon composite material, and a negative electrode plate containing same, relating to the field of silicon-based composite materials. The silicon composite material comprises silicon nanoparticles, carbon nanotubes, silicon oxide, lithium oxide, and lithium metasilicate. The carbon nanotubes and the silicon nanoparticles are dispersed and cross-linked to form a three-dimensional network structure. Silicon oxide, lithium oxide, and lithium metasilicate cover the three-dimensional network structure to form secondary particles. The secondary particles and graphite are homogenized and coated according to a specific particle size ratio to prepare the negative electrode plate containing the silicon composite material and having high-capacity development, good conductivity, high coulombic efficiency, small volume expansion, and high cycling stability.

The embodiment of the invention discloses a positive electrode active material, a positive electrode plate and a lithium ion battery, the positive electrode active material comprises a first active substance and a second active substance, the mass percentage of the first active substance is 10-40%, and the mass percentage of the second active substance is 60-90%. The median diameter D1 of the first active material and the median diameter D2 of the second active material meet the following formula: 2 * D1 < = D2; according to the invention, by controlling the particle size ratio and the mass ratio of the two active substances, the first active substance is filled into the gaps of the second active substance, so that the particle stacking density is improved microcosmically, and the powder compaction density of the positive pole piece is remarkably improved macrocosmically.

The invention discloses a metallurgical solid waste synergistic mineralization carbon sequestration and high-performance carbon capture method, which comprises the following steps: crushing and grinding steel slag and red mud until the particle size is 80-100 microns and the specific surface area is 4000-4500 cm < 2 > / g, and mixing according to a mass ratio of 7: 3 to obtain a mixed solid waste raw material; premixing the mixed solid waste raw material with water according to a liquid-solid ratio of 10-15 mL / g to form slurry; placing the slurry in a mineralization reactor, introducing CO2 gas, and carrying out synergistic mineralization reaction for 6-8 hours under the conditions that the temperature is 80-120 DEG C, the CO2 concentration is 60-100%, the gas flow rate is 500-700 mL / min and the relative humidity is 50-70%. Compared with the prior art, through component complementation, alkali excitation of the red mud on the activity of the steel slag, calcium guarantee of the carbon sequestration capacity of the steel slag and a synergistic system, the mineralization efficiency is remarkably improved, and the maximum mineralization efficiency can exceed a theoretical addition value 23.3%. The actual carbon sequestration amount of the mixed sample can reach 310-450g CO2 / kg of the mixed sample, and is far higher than the theoretical addition value. Meanwhile, solid waste is consumed, CO2 is fixed, and a feasible carbon emission reduction and solid waste treatment integrated technical path is provided for the metallurgical industry.

The invention provides a radiation refrigeration film and a preparation method thereof. The thin film sequentially comprises a substrate layer, a form regulation and control layer, a reflection layer and a protection layer from bottom to top. The form regulation and control layer comprises inert particles and a resin material, and the resin material is used for fixing the inert particles, so that a concave-convex rough surface with the surface roughness Ra of 0.5-5 microns is formed on one side, close to the reflecting layer, of the form regulation and control layer; and the reflecting layer is a metal film and is directly formed on the rough surface of the form regulation and control layer, and the morphology of the reflecting layer is copied to form a low-gloss diffuse reflection structure. The beneficial effects of high sunlight reflectivity, high infrared emissivity and low glossiness are achieved by accurately controlling the particle size ratio of particles of the form regulation and control layer and the dry film thickness ratio, and the whole-process preparation method is simple, low in cost, suitable for large-scale production and wide in application prospect in the fields of building energy saving, carrying tools, electric power systems and the like.

The invention belongs to the technical field of metal additive manufacturing, and particularly relates to a method for detecting the particle size of powder for additive manufacturing. The method comprises the following steps: before detection, mixing to-be-detected powder in an inert gas protection tank, mixing the mixed to-be-detected powder with a dispersing agent, and fully dispersing the mixed suspension by adopting an ultrasonic technology; placing the dispersed suspension liquid in detection equipment, enabling the suspension liquid to flow to a high-speed camera through a pipeline, detecting particles in the suspension liquid by adopting the high-speed camera, and obtaining the size and total quantity of the particles, the quantity of particles exceeding a specific size and particle morphology picture information; and according to the statistical result, the particle size ratio of the powder for additive manufacturing is calculated. According to the characteristics of the powder for additive manufacturing, a wet method is adopted for detecting the particle size of the powder for the first time, a high-speed camera is used for collecting the size, the number and the image of the powder, the particle size ratio of the powder is calculated based on the results, and the particle size ratio of the powder for additive manufacturing can be accurately and rapidly detected.

The invention relates to the technical field of electronic packaging materials, in particular to a high-thermal-conductivity insulating polymer-based composite material and a preparation method thereof.The high-thermal-conductivity insulating polymer-based composite material comprises a thermal conductive filler of a stacking factor and a polymer matrix, the filler is a multi-scale inorganic particle mixture, the maximum / minimum particle size ratio of the filler is smaller than or equal to 10, and the filler is blended with the matrix after being subjected to surface coupling treatment; the thermal conductivity of the obtained composite material is greater than or equal to 3.5 W / (m.K), and the volume resistivity is greater than or equal to 1 * 1014 omega.cm The material is used for injection molding packaging of an inductor, can be molded at a low voltage of 30-80 MPa, effectively reduces temperature rise, avoids coil damage, and improves reliability under high frequency and large current.

The present invention aims to provide solder-coated metal particles in which further stabilization of the solder-coated metal particles is achieved, a more concentrated particle size distribution (cumulative volume distribution curve) is exhibited, and the solder layer exhibits a melting point of 170°C or lower, and a method for producing solder-coated metal particles. The solder-coated metal particles have: spherical metal particles formed of Ni, 1 mass% or more and 15 mass% or less of P, and unavoidable impurities; and a solder layer formed of Sn, 40 mass% or more and 67 mass% or less of Bi, and unavoidable impurities, which coats the metal particles, and in a cumulative volume distribution curve obtained by a laser diffraction scattering method for a powder composed of the solder-coated metal particles, a particle size ratio (d90-d50) / d50 calculated from a particle size d50 at which the cumulative volume is 50% and a particle size d90 at which the cumulative volume is 90% is 1.5 or less.