There are many factors influencing the test effect of laser particle size analysis instrument. This article discusses the following three key factors: light path alignment, instrument calibration, and sample dispersion. First , light path alignment Alignment means that the focus of the laser beam passes through the center of the photodetection array. The laser particle sizer must first ensure that the focus of the laser beam passes through the center of the photodetector array before the test and does not shift during the test to obtain correct results. At present, the particle size analyzer adopts two-dimensional alignment systems. Stepping motors are generally used to drive power through the sleeves to drive the moving ruler. Stepping motors and shaft sleeves, sleeves and moving rulers are connected through the top wire. The center of the three devices is not on a straight line, and the idle gap between the positive and negative movements of the moving ruler is large, causing the centering system to be unstable and the alignment cannot be completed quickly and accurately. The existing alignment systems are Without a limit system, if there is a problem with the optical path itself, misalignment will occur in the alignment system and the mechanical transmission components will always be moved in one direction. In response to the deficiencies of the existing technologies, Micron Corporation provides a three-dimensional automatic alignment system that is rationally designed, simple and compact in structure, and easy to use. In order to improve the accuracy of the alignment system and reduce the idle length, a stepper motor with a screw is used as a power component. In order to improve the stability of the alignment system, an anti-backlash slide is used as the core component of the mechanical transmission assembly. In order to improve the centering speed and prevent misoperation, the photoelectric sensor is used in combination with the limiting piece to limit the position. Compared with the existing technology, the new three-dimensional automatic alignment system has the following superior features: 1 , to achieve a three-dimensional automatic alignment. 2 , the design is reasonable, simple and compact structure. Convenient and practical, can be used for various models of laser particle size analyzer. 3. The combination of a stepper motor with self-threaded screw and an anti-backlash rail can achieve the three-dimensional alignment requirement in a stable, fast, and accurate manner. 4 , using the photoelectric sensor and limiting piece combined way to limit, to prevent damage to the drive system due to optical path problems. Second , the instrument calibration It is worth mentioning here that instrument calibration is not just a matter of correcting the accuracy of the instrument using the national standard material. The instrument calibration should include the following aspects: 1 , the instrument optical benchmark Calibration of the instrument makes sense only if the instrument's optical system is working properly. The optical window is an important part of the laser particle size analysis instrument. Therefore, before and after the test, the inside and outside surfaces of the optical window should be kept clean, free of scratches, clean and free of defects. The optical reference spectrum transitions smoothly and in sequence, with no significant protrusions or depressions. 2. Influence of external conditions on the instrument The external conditions mainly include the influence of environmental humidity, temperature and power supply voltage fluctuations on the instrument test results. 3 , instrument measurement repeatability The instrument was preheated to a predetermined time period, adopt a national standard for multiple tests, the test sample is generally 6--10 times, recording each D50, calculated measuring mean, standard deviation and relative standard deviation. 4 , the relative error of the instrument measurement Different from the reproducibility measurement of the instrument, the relative error of the instrument should be tested with at least three kinds of national standard substances. Each sample should be measured three times and averaged separately to obtain the average value of multiple particle size measurements. , Calculate the relative error between the average value of the instrument measurement and the standard value of the reference material of the particle size table. 5 , instrument resolution The judgement of the instrument's resolution is to use the method of testing two kinds of samples for mixing test. The removal amount of two kinds of particle size reference materials should be determined according to their mass concentration, so as to ensure that the mass concentration ratio of reference material in the mixed sample is 1 : 2 . Mix the sample and add it to the instrument for measurement. Two separate unconnected peaks should be observed from the instrument's particle size distribution and the two peaks are considered separate. Third, the sample dispersion 1 〠Influence of powder solution concentration on measurement results Distilled water was used as a dispersion medium and no surfactant was added. 3 parts of carborundum sample solution with different concentrations were prepared , ultrasonically agitated for 1 min , and then the particle size was measured. When the powder sample concentration is small, the measured particle size is small, and the particle size distribution range is also narrow (as can be seen from the particle size distribution curve ) ; when the concentration of the powder sample is large, repeated scattering and particles are easy. Agglomeration, the measured particle size is too large, a wide range of particle size distribution (as can be seen from the particle size distribution curve ) , the test result error is large. However, the above results do not indicate that the smaller the concentration of the powder sample, the better, because when the concentration is small to a certain extent, the particles in the sample have been greatly reduced, too few particles will produce larger sampling and measurement random error, then The sample has no representative, so the lower limit range of the concentration should be controlled during measurement. Under the general test conditions, the sample shading is generally 10 % to 15 % of the instrument . 2 , the impact of the dispersion time on the measurement results Distilled water was used as a dispersion medium and no surfactant was added. 3 samples of a certain concentration of the sample solution were prepared and dispersed by an ultrasonic disperser at different times. Then the particle size was measured. The results showed that the dispersion time was longer in a certain period of time. The effect is small, but the broken sample should also be considered. 3 , the impact of dispersion medium on the measurement results When the particle size of the powder is tested, the selected dispersion medium should not only have a wetting effect on the powder, but also be low in cost, non-toxic, and non-corrosive. Commonly used dispersion media are water, water + glycerol, ethanol, ethanol + water, ethanol + glycerol, cyclohexyl alcohol, etc. When the powder is coarse, water or water plus glycerol can be used as the dispersion medium. When the powder is fine, ethanol or ethanol can be used. Add water as a dispersion medium. Ethanol infiltrates more strongly than water, making it easier to fully disperse the particles. 4. Effect of the type and concentration of dispersant on the determination result The selection of suitable dispersants is a hotspot in current research, and surfactants are the most used in dispersants. The types of surfactants mainly include: anionic surfactants, cationic surfactants, amphoteric surfactants, non-ionic surfactants, special types of surfactants, and the like. Powders are usually charged in water. Adding surfactants with the same kind of charge hinders the surface adsorption due to the mutual repulsion between the charges, so that the powder can be dispersed. Different surfactants have different effects on the dispersion of different kinds of powders. In the determination, it is necessary to compare the dispersion effects of several surfactants and finally determine the most ideal surfactant. The concentration of the dispersant also has a certain influence on the measurement result, and should be controlled when used. Taking polyacrylamide as an example, the glass powder dispersion effects at different dispersant concentrations were compared. During the test, it was found that when the dispersant concentration was too high, flocculation occurred in the solution ( this is also one of the reasons for the increase in the particle size determination results ) . 5 , the influence of the temperature of the powder sample solution on the measurement result Distilled water was used as a dispersion medium. Without surfactant, 6 parts of the slag powder sample solution with the same concentration were prepared and dispersed for 5 min using an ultrasonic disperser . They were tested at different temperatures, and the particle size was changed with increasing temperature. Small trend. This is because the high temperature is favorable for the dispersion of the particles, and the low temperature causes the particles to be easily agglomerated, which increases the measurement error. However, the test temperature should not be too high, because the trend of particle size reduction above 35 °C is not obvious, and the particle size analyzer is not suitable for operation at high temperatures. It can be seen that the temperature of the powder sample solution should be kept in the range of 20 to 35 °C. From the above it can be seen that to use the laser particle size analyzer to accurately test the particle size of a sample, it is necessary to study the very factors.
Jiaxing Ganland Auto Parts Co., Ltd 's one of the main products is Door Rubber Seal Gasket.Such as Door Seal Gasket. It has T shape, H shape with different sizes. The material has Solid PVC material and NBR material. For the color, we have gray color, white color and black color. It has permanet complexed shape acoss section. We have different thickness sizes. The length has 5 meters and 6 meters.
We have many big clients in domestic, like CIMC, DONGFENG etc. Also we have many clients overseas. For more information, you are warmly welcome to send us an email. We will feedback to you ASAP.
Van Pvc H Profile,Truck Door Sealing Strip,Container Door Rubber Seal,Door Seal Gasket Jiaxing Ganland Auto Parts Co., Ltd. , https://www.gltruckparts.com