Particle size testing is a test crop that characterizes powder particle size characteristics through specific instruments and methods. The use of powder in people's nightlife and industrial production is very common. Such as flour, fire mud, plastics, paper, rubber, ceramics, medicines and so on. In the different use domains, the requests for powder properties are different. In all the indicators of the powder characteristics, the particle size distribution is the most concerned index in all the categories of use. Therefore, the particle size distribution of subjective real-world reaction powders is a common agricultural work. The above detailed knowledge of the basic knowledge and basic methods for particle size testing.
First, basic knowledge of particle size testing
1. Particles: How many bodies of a particular shape exist outside a size range. The size of the road outside is usually between millimeters and a meter, and the particles are not only solid particles, but liquid particles such as droplets and oil beads.
2, powder Qi: from a large number of particle groups with no different size particles defeated.
3, particle size: The size of the particles called particle size.
4. Particle size distribution: The percentage of the powder component is not the percentage of particles with different particle sizes that are not reflected by the specified instrument and method. There is no interval distribution warfare and distribution of two types of situations. Interval distribution, also known as differential distribution or frequency dispersion, shows the percentage of particles exposed outside the particle size range. The cumulative distribution is also the sound integration fabric, which exhibits greater or less than the percent dew point of a certain particle size.
5, the representation of the particle size distribution:
(1) Form method: Using Rieger's method to distribute the particle size ranges and eliminate the total number of sheets.
2Graphics method: The method of expressing the particle size distribution in the form of histograms and straight lines at the top of a rectangular system.
3 function method: use a number of teaching function to express the granular distribution. This type of method is usually used in actual discussions. If the famous Rosin-Rammler distribution is a non-function combination cloth.
6, particle size warfare equivalent particle size:
The particle size is the particle diameter. This concept is very simple and clear, so what is the equivalent particle size, what is the particle size and equivalent particle size closure? We know that Google optimization, as long as the sphere has a diameter, the other shape of the body It is not diameter, but the particles of the group defeated the powder and continued to be a large number of not square spheres, but a variety of irregular shapes, flaky, needle-like, less prismatic and so on. These complex shape particles can't indirectly use diameter to reflect its size. In practice agriculture, diameter is the most intuitive and most plentiful quantity to describe a small particle. People also hope to use such a quality to describe particles. Therefore, we introduced the theory outside the theory of particle size testing. Effective particle size of this idea.
The equivalent particle size means that when a certain physical characteristic of a particle is the same as or equal to the same amount of spherical particles, we use the diameter of the spherical particle to represent the diameter of the actual particle. The particle size of this spherical particle is the equivalent particle size of the actual particle. The equivalent particle size is as follows:
1 Equivalent volume diameter: Take the labyrinth diameter of the ball with the same particle volume. It is generally assumed that the diameter measured by the laser method replaces the equivalent volume diameter.
2 Equivalent weight fast path: On the contrary premise, the maze of the ball that is identical to the rapid fall of the practice particle. The particle size measured by the sinking method is the equivalent weight fast path, and also the Stokes diameter.
3 Equivalent resistance diameter: The diameter of the spherical particle with the opposite resistance from the real intergranular particles on the premise of the total phase. The particle size measured by the library I special method is the equivalent resistance diameter.
4 equivalent injection area diameter: The diameter of the spherical particle that is opposite to the input area of the real particle. The size of the particle size measured by the hidden back mirror method and the image method is the equivalent projection area diameter.
7, how many key features of the performance of granularity:
1D50: The particle size at which the percentage of cumulative particle size distribution of a sample reaches 50%. Its physical meaning is that particles with a particle size larger than 50% account for 50% of particles with smaller particles, and D50 also have a median or median diameter. D50 is rarely used to indicate the uniform size of the powder.
2D97: Particle size for a sample when the number of counted particle size distributions reaches 97%. Its physical meaning is that 97% of the particles have a particle size larger than it. D97 is rarely used to indicate a fine grain size index.
The definition and physical meaning of other parameters such as D16 and D90 are similar to those of D97.
3 than the outer surface product: the two-dimensional component of the surface of the grain of the war. Than the external surface of the double for m2/kg or cm2/g. There is no closed system for the particle size of Biriri collection, the coarser the granularity, the smaller than the external product, but that kind of relationship is not necessarily inversely closed solution.
8. The singleness of the particle size test: the biased preference of a sample is measured repeatedly. Repetitiveness refers to the most important means of weighing a granular test instrument and method. Its disk algorithm is not:
Among them, n is the main number of measurement (generally n=10);
Xi is the typical value of each main test result (generally D50 value);
x The uniform value of the exemplary values of multiple test results;
σ is the scale difference;
δ is a repetitive absolute error.
Influencing the granularity test sinks the elements of the instrumentality and method itself; the sample prepares the preserved fruit in the circle; the environmental attraction does the round element. The granularity test when there is good repeatability is the basic request for equipment and personnel.
9, the granularity of the test:
The usual measuring instruments have indicators of accuracy. Because of the special nature of the particle size test, the use of actuality returns the meaning of correctness. Because the particle size measured by the particle size test is equivalent to the particle size, for a single particle, an equivalent method that is not common can lose different equivalent particle sizes and turn it on three sides.
No, because the measurement method is different, one particle loses two different results. That is, an irregular grain, if a value is used to represent its size, this value is not unique, but a series of values. For each test method, one of a series of values that represent the size of the particle is entered for a particular circle of the particle. The lost value is one of a series of values that can represent the size of the particle. The difference in the outcome is due to subjective reasons. The more complex the shape of the particles, the better the results of different test methods. However, this does not mean that the out-of-granulation test result can be marginal, but there should be certain solidity, that is, it should be compared with the actual particle size distribution of the real-world reaction sample. After the actual nature of the program, we must adopt a non-rigorous scale, which is a qualitative overview. However, some scenes can serve as a good basis for testing the results. For example, the measurement result of the instrument on the scale should be outside the allowable error range of the nominal value; the sample destroyed by destruction should be coarser than that destroyed by powder crushing; the large particle exposure of the sample after classification should be reduced; There are differences in methods such as industry norms or parental recognition.
