What are the requirements for particle size of powder in all walks of life?
I want a narrower grain size distribution!I want granules!I want bigger particles!I want a smaller particle!The requirements for particle size and particle distribution are different in different application fields.Narrow distribution, wide distribution?Large particles, small particles?Which kind do you want in the end, below collates the application case data of different industries to explain for you.
Case 1: Requirements for particle size distribution of cement particles
Cement is a typical powder material, and the particle size distribution of cement particles is closely related to its application properties.In the cement industry, usually put the cement particle size distribution is called "particle grade".Because the cement particles only react with water, there is a gelling effect, and the part that has not been hydrated only plays a skeleton role.The research shows that the particles less than 1μm are completely hydrated in the mixing process with water, which does not contribute to the strength of the concrete pouring body. It belongs to over-grinding and wastes energy.However, the particles larger than 90μm are only hydrated on the surface and only act as fillers, losing the properties of cement itself.The research on the hydration progress of cement particles with different sizes at different ages shows that reasonable particle size distribution is an important guarantee of cement quality.This is different from most powder materials, the narrower the particle size distribution, the better.
Case 2: Particle size requirements for aerosols
Aerosol treatment is a treatment in which drugs are made into small droplets or particles, known as aerosols, that go directly to the respiratory tract and lungs as you breathe. They are often used to relieve respiratory problems such as asthma and cough.The in vivo efficacy of inhalant aerosols is mainly affected by the physical properties of drug molecules, especially the particle size and distribution of drug molecules.
In general, particles larger than 10um will deposit in the mouth and throat, particles smaller than 10um and larger than 5um will deposit in the upper bronchus, and particles from 1 to 5um May deposit in the base of the lung or alveoli.Particles smaller than 0.8um are exhaled out of the body when exhaled.
Case 3: Relationship between texture and grain size of chocolate
Chocolate is a favorite dessert for many people. The combination of the unique taste of cocoa and auxiliary ingredients such as granulated sugar and milk powder brings great pleasure to people's taste buds.However, this delicious taste is not only dependent on the flavor of the food, because chocolate itself is a multi-phase dispersion system of ultra-fine particles, sugar and can be small plasmids as the dispersed phase in the oil continuous phase, so the "granularity" of its taste plays a decisive role.For example, having fewer large particles makes for a smoother, smoother taste.
Case 4: Relationship between low temperature sintering and particle size of alumina ceramics
The melting point of alumina is as high as 2050℃, leading to the sintering temperature of alumina ceramics is generally high, so that the manufacture of alumina ceramics needs to use high temperature heating element or high quality fuel and senior refractory materials for kiln and kiln furniture, which to a certain extent, limits its production and wider application.Therefore, reducing the sintering temperature of alumina ceramics, reducing energy consumption, shortening the firing cycle, reducing the loss of kiln furnaces and kiln furniture, so as to reduce the production cost, has been an important issue that enterprises are concerned about and need to solve urgently.At present, the low temperature sintering technology of various alumina porcelain is summarized, mainly from the raw material processing, formula design and firing technology to take measures in three aspects.It is a feasible method to reduce the sintering temperature of ceramic body by reducing the particle size of alumina powder and improving the activity of the powder.
