Comparison Table of Various Particle Sizes of Artificial Diamond Crushed Material and Micropowder:

　　1、Related concepts:

1.Particle size and particle size:The size of a particle is called particle size,which is generally represented by its diameter,hence it is also known as particle size.

2.Particle size distribution:Using a certain method to reflect the percentage of particles in a series of different particle size intervals in the total amount of the sample is called particle size distribution.

3.Equivalent particle size:Due to the fact that the actual shape of particles is usually non spherical,it is difficult to directly represent their size with diameter.Therefore,in the field of particle size testing,for non spherical particles,the equivalent particle size(commonly referred to as particle size)is usually used to characterize the particle size.Equivalent particle size refers to the use of the diameter of a spherical particle to represent the actual diameter of a particle when its physical properties are the same or similar to those of a homogeneous spherical particle.According to different principles,the equivalent particle size can be further divided into the following categories:equivalent volume size,equivalent sieve size,equivalent sedimentation rate size,and equivalent projected area size.It should be noted that various testing methods based on different physical principles have different definitions of equivalent particle size,so there is no direct comparison between the measurement results obtained by various testing methods.4.Common terms for particle size grading:nanoparticles(1-100 nm),submicron particles(0.1-1μm)Particles,powders(1-100μm)Fine particles,fine powder(100-1000μm)Coarse particles(greater than 1 mm).

5.Average diameter:Data representing the average particle size.According to the particle size distribution measured by different instruments,such as average particle size distribution,volume average diameter,area average diameter,length average diameter,quantity average diameter,etc.

6.D50:Also known as median or median particle size,this is a typical value that represents particle size.This value accurately divides the population into two equal parts,meaning that 50%of particles exceed this value and 50%of particles fall below this value.If D50 of a sample is 5μm.Explanation:Among all particles with a particle size greater than 5 that make up the sampleμParticles of m account for 50%,less than 5μThe particles of m also account for 50%.

7.Most frequent particle size:refers to the particle size value corresponding to the highest point of the frequency distribution curve.

8.D97:D97 refers to the particle size corresponding to the cumulative particle size distribution of a sample reaching 97%.Its physical meaning is that 97%of particles have a particle size smaller than it.This is a widely used data for representing the coarse end particle size index of powders.

　　2、Basic Methods and Analysis of Particle Size Testing

　　Laser method

The laser method is a multi-purpose instrument to measure the particle distribution of suspension,lotion and powder samples through a laser scattering method.Nanometer and micrometer laser particle size meters can also analyze the shape of particles through installed software.Now it has become the mainstream of particle testing.

1.Advantages:(1)Wide applicability,capable of measuring both powdered particles and particles in suspensions and emulsions;(2)The testing range is wide,and the international standard ISO 13320-1 Particle Size Analysis 2 Laser Diffraction Method 2 ods 2 Part 1:General Principles specifies that the application range of laser diffraction scattering method is 0.1-3000μM;(3)High accuracy and good repeatability;(4)Fast testing speed;(5)Online measurement is possible.

2.Disadvantage:It is not suitable to measure samples with narrow particle size distribution,and the resolution is relatively low.

　　Classification of laser scattering technology:

1.Static light scattering method(i.e.time averaged scattering):The spatial distribution of scattered light is measured using the Mie theory.The effective lower limit of the test can only reach 50 nanometers,and it is powerless for smaller particles.The testing of nanoparticles must use”dynamic light scattering”technology.

2.Dynamic light scattering method:Study the variation of the intensity of scattered light at a fixed spatial position over time.The principle is based on the ISO 13321 standard method for analyzing particle size,which utilizes the dynamic scattered light generated by moving particles to analyze the particle size of PCS through photon correlation spectroscopy analysis.

According to the scattering signal received by the instrument,it can be divided into diffraction method,angular scattering method,total scattering method,photon correlation spectroscopy method,photon cross correlation spectroscopy(PCCS)method,etc.The laser diffraction scattering particle size analyzer(commonly referred to as the laser particle size analyzer),which uses laser as the light source,is the most mature and has been widely adopted in particle measurement technology.

　　Laser particle size analyzer:

　　Figure 1:Block diagram of laser particle size analyzer device

　　Settlement method

The settlement method can be further divided into:settlement balance,transparent settlement,centrifugal settlement,etc.Hydrometer method(also known as densitometer method):It is a type of settlement analysis method,and there is also pipette method(also known as pipette method).The theoretical basis of these two methods is based on Stokes’law,which states that the settling speed of spherical fine particles in water is proportional to the square of the particle diameter.

　　Following Stokes’law:

A method of measuring particle size distribution based on the different settling velocities of particles with different particle sizes in a liquid.Its basic process is to place the sample in a certain liquid to make a suspension of a certain concentration,and the particles in the suspension will settle under the action of gravity or centrifugal force.The settling speed of large particles is faster,while the settling speed of small particles is slower.Stokes’law is the basic theoretical basis for particle size testing using sedimentation method.

　　Figure 2:Schematic diagram of settlement method principle

1.Advantages:This method is a traditional powder particle size testing method in industries such as coatings and ceramics.

2.Disadvantage:Slow measurement speed,unable to handle mixtures of different densities.The results are greatly influenced by environmental factors(such as temperature)and human factors.

　　Sieving method

The sieving method is to use a set of standard sieves,such as pore diameter(mm):20,10,5.0,2.0,1.0,0.5,0.25,0.1,0.075,to stack sieves of different sizes according to the particle size and distribution range of the tested sample for sieving,collect the residue of each sieve,and weigh to obtain the particle size distribution of the tested sample by weight.Pour 200 g of representative samples that have been dried and dispersed into a standard sieve and shake them,then weigh the soil left on each sieve and calculate the relative content of each particle group to obtain the soil particle grading.

　　1.Advantages:Low cost and easy to use.

2.Disadvantage:For sizes smaller than 400 mesh(38μm)The dry powder is difficult to measure.The longer the measurement time,the smaller the result obtained.Unable to measure jet or emulsion;This can result in some strange results when measuring needle like samples.Difficulty in providing detailed particle size distribution;The operation is complex,and the results are greatly influenced by human factors;The so-called number of mesh of a certain powder refers to the amount of residue after sieving with that mesh being less than a given value.If the sieve residue is not specified,the meaning of”eye”is vague and inconvenient for communication.

　　Figure 3:Schematic diagram of the principle of screening method

　　Microscopic method

During this method of testing,the sample is coated on a glass slide,and the imaging method is used to directly observe and measure the plane projection image of the particles,thereby measuring the particle size.Capable of measuring the projected area of particles one by one to determine their particle size,with a measurement range of 150-0.4μm.The lower limit of particle size for electron microscopy can reach 0.001μM or smaller.Microscopic method belongs to imaging method and uses different equivalent representations.Therefore,there is no direct comparison between the test results of the microscope method and other measurement methods.It is the most basic and practical measurement method,often used as a verification and calibration for other measurement methods.However,such instruments are expensive,sample preparation is cumbersome,and measurement time is long.If only the particle size is tested,this method is generally not used.But if it is necessary to understand both the size of particles and their shape,structural condition,and surface morphology,this method is the best testing method.

The commonly used ones include SEM(scanning electron microscope),TEM(transmission electron microscope),and AFM(atomic force microscope).

For example,in top journals,these methods are commonly used for material morphology and particle size analysis:

　　SEM:

Figure 4:SEM image of template polystyrene(PS)spheres[1]

　　TEM:

Figure 5:TEM image and diameter distribution statistics of silicon microspheres[2]

　　AFM:

Figure 6:AFM image of graphene oxide[3]

　　Ultrasonic particle size analysis

The RF generator emits ultrasonic waves of a certain frequency and intensity,passing through the testing area and reaching the signal receiving end(RF detector).When particles pass through the testing area,due to the varying absorption of sound waves by particles of different sizes,the attenuation degree of sound waves obtained at the receiving end also varies.Based on the relationship between particle size and ultrasonic intensity attenuation,the particle size distribution can be obtained,and the solid content of the system can also be measured.

Figure 7:Schematic diagram of the principle of ultrasonic particle size analyzer

X-ray powder scattering method(XRD)

　　Calculate using the Xie Le formula:

(K is the Scheler constant,D is the average thickness of the grain perpendicular to the crystal plane direction,B is the measured sample diffraction peak half widthθIs the diffraction angleγIs the X-ray wavelength,usually 0.154056 nm)

K is the Scheler constant,and if B is the half width of the diffraction peak,then K=0.89;If B is the integrated height width of the diffraction peak,then K=1;D is the average thickness of the grain perpendicular to the grain plane direction(nm);

B is the width at half height of the diffraction peak of the measured sample(which must be corrected for bilinear and instrumental factors),which needs to be converted into radians(rad)during the calculation process;

θDiffraction angle,also changed to radian system(rad);

γIs the X-ray wavelength,which is 0.154056 nm.

1.Advantages:This method has a simple and easy testing process,and is widely used in grain estimation in crystal materials.

2.Disadvantage:The test results of this method are relatively rough and not suitable for amorphous materials.

　　Particle image method

1.The particle image method has two testing methods:static and dynamic.

2.Using a modified microscope system in a static manner,combined with a high-definition camera,the image of the particle sample can be intuitively reflected on the computer screen.With relevant computer software,particle size,shape,overall distribution,and other attributes can be calculated

3.The dynamic method has dual analysis capabilities for morphology and particle size distribution.We have rebuilt a brand new cyclic dispersion system and software data processing module,solving the problems of sample preparation,poor sampling representativeness,and particle adhesion in static particle imagers

　　Figure 8:Schematic diagram of particle imager

Principle:The stroboscopic light emitted from the stroboscopic light source passes through a beam expander to obtain parallel stroboscopic light.In the test area,the stroboscopic light shines on a dispersed individual particle,and through a patented optical imaging system,a clear image of each particle and the particle size distribution of all samples are obtained

　　Kurt resistance method

The Kurt resistance method has been widely applied in fields such as biology and has become a testing standard for abrasives and certain industries.According to the changes in resistance at the pore opening caused by particles of different sizes passing through a small hole in the electrolyte,the particle size is characterized and measured by the changes in resistance.It can measure the number of particles,so it is also known as a Kurt counter.It has high measurement accuracy and good repeatability,but it is prone to clogging of the orifice,usually ranging from 0.5 to 100μBetween m.

The resistance method instruments all use negative pressure siphoning to force the sample through the gemstone micropores.The small cylindrical gemstone micropores are filled with a medium to form a constant liquid resistance(R0).When a spherical standard particle with a diameter of d passes through the gemstone micropores in the sample,an increase in resistance is generated due to the fact that the resistivity of the particle is greater than the resistance of the mediumΔAccording to Kurt’s formula,the output voltage pulse of the resistance method sensor is also proportional to the volume of the particles.

1.Advantages:(1)High resolution:able to distinguish subtle differences in particle size between particles.The resolution is the highest among various existing particle size instruments.(2)Fast measurement speed:It usually only takes about 15 seconds to measure a sample.(3)Good repeatability:measuring around 10000 particles at once has good representativeness and high measurement repeatability.(4)Easy to operate:The entire measurement process is basically automatic and easy to operate.

2.Disadvantages:(1)Small dynamic range:For the same small hole tube,the ratio of the maximum to minimum particles that can be measured is approximately 20:1.(2)It is prone to blockage failure.Although the new counter has an automatic blockage removal function,it affects the smoothness of measurement.(3)The lower limit of measurement is not small enough:the minimum aperture of a small hole tube that can be used in reality is 60μAround m,therefore the lower measurement limit is 1.2μAbout m.

　　3、Selection of particle size analyzer

1.Test range:The test range refers to the area between the upper and lower limits of the particle size analyzer.The actual sample size range should preferably be in the middle of the instrument’s measurement range.A certain margin should be left for the testing scope.

2.Repeatability:Repeatability is the main indicator of the quality of an instrument.It is most realistic to verify the repeatability of the instrument through actual measurement methods.When comparing repeatability,three values,D10,D50,and D90,are generally used.

3.Purpose:Due to the unique performance of different particle size analyzers,more suitable instruments can be selected according to different needs.For example,if there is a large amount of testing and a variety of samples,a laser particle size analyzer should be used.If there is a small amount of testing and a single sample,a sedimentation particle size analyzer can be selected.It is necessary to understand the particle morphology and other special indicators,and choose an image analyzer.

4.Consistent with industry habits and major clients:Due to the unique nature of particle size testing,the test results of different particle size instruments often have deviations.To reduce unnecessary trouble,a particle size analyzer that is consistent with industry habits and major customers(with the same principle or even model)should be selected.

　　4、Summary

Granularity testing is a highly professional and technical task.This work has a significant impact on the production process and product quality control of powder products,and has high requirements for personnel,instruments,and the environment.Understanding the basic knowledge and methods of granularity testing has certain practical significance for doing well in granularity testing work.

Product Classification:Comparison Table of Various Particle Sizes of Artificial Diamond,Crushed Material,and Micropowder: