Powder in life
No powder is not a material. Powder is the foundation of modern industry, the most important technical support force for high-tech industry, the most important cornerstone of modern defense industry, and the most basic raw material for all walks of life. Powder is everywhere and is closely related to our lives.
The term powder first appeared in the early 1950s. It is characterized by many discontinuous surfaces, a relatively large specific surface area, and is composed of many small granular materials. In a further generalization, powder is an aggregate composed of countless relatively small granular substances.
Powder refers to a collection of solid fine particles, <100μm is powder (dust), >100μm is (particle).
Powder exists in liquid, gas, and solid forms. The powder usually refers to a small-sized solid. The solid substance is divided into a dispersed state and an aggregate state. Most powders are in a dispersed state.
Basic properties of powder
- The geometric properties of the powder: the size, particle size distribution, particle shape, and accumulation state of the powder particles.
- Mechanical properties of powder: friction angle of powder, powder pressure, fluidity and movement properties in fluid.
- Other physical and chemical properties of the powder: the electrical, magnetic, optical, acoustic, and thermal properties of the powder, as well as its adhesion, adsorption, cohesion, wettability, and explosive properties.
Classification of powder
According to the cause, it can be divided into natural powder and artificial powder. According to the preparation method, it can be divided into mechanical crushing method and chemical method powder. According to the particle size, it can be divided into primary particles, aggregate particles, aggregate particles, and floc particles. According to the dispersion state, it can be divided into coarse powder (>0.5mm), medium and fine powder (0.074~0.5mm), fine powder (10~74μm), fine powder (0.1~10μm), nano powder (<100nm).
Common powder materials
Metal powders include reduced iron powder, zinc powder, copper powder, nickel powder, and aluminum powder. Non-metal powders include perlite, diatomaceous earth, tourmaline, icelandite, brucite, organic materials, natural rubber, and synthetic fibers. , Starch, cellulose, synthetic resin, inorganic materials include calcium carbonate, silicate, aluminate, phosphate, silicon powder.
In addition, there are carbon-based materials such as carbon black, graphene, carbon fiber, nanomaterials, composite materials, and powdered Chinese medicine.
Powder technology
- Preparation: various physical, chemical and mechanical methods.
- Processing: crushing, classification, dispersion, mixing, granulation, surface treatment, fluidization, drying, forming, sintering, dust removal, dust explosion, transportation, storage, packaging, etc.
- Test: Characterization of various geometric mechanical, physical and chemical properties of powder.
Powder in life
- Clothes
The different colors of clothes are due to the addition of oxides, chromates, sulfates, silicates, hydroxides, sulfides, metals, etc. Different powder materials can be used to make various buttons, such as resin buttons, ceramic (zirconia) buttons, plastic buttons, metal buttons (copper), etc. Adding calcium carbonate, kaolin, talc, barite and other powders to rubber shoes can enhance the tensile strength and wear resistance of the shoes. Adding nano titanium dioxide, nano zinc oxide, nano silicon oxide, etc. can inhibit bacteria and deodorize the worn socks. Adding carbon black, tin dioxide, zinc oxide, titanium dioxide, etc. can make clothes antistatic; adding some far-infrared nano ceramic powder can make clothes warmer.
Common food flour, soy milk, milk powder, coffee, salt, etc. are all powders; baking soda is needed to make bread and steamed bread; medical stone mineral water is called a treasure in mineral water; zeolite has also been developed as a health product. For anti-aging, remove heavy metals accumulated in the body. Commonly used bezoar detoxification pills and heat-clearing detoxification granules may be added with talc, lumps, pumice, alunite, arsenic, gypsum, etc.; aseptic tableware and aseptic food packaging made of nano-materials are already available.
- Residence
cement. Diatom mud with diatomaceous earth as the main raw material has good air purification and formaldehyde adsorption functions. Perlite insulation board is not only light in bulk density, but also high in strength, suitable for all kinds of buildings. Commonly used architectural coatings are added with kaolin, sepiolite, bentonite, gypsum powder, quartz powder, etc. Refractory materials such as silicon, magnesia, and carbon are used in various constructions.
- Travel
Carbon fiber, aluminum, and magnesium help reduce the weight of vehicles and airplanes; car tires, seats, steering wheels, etc. are filled with calcium carbonate, wollastonite powder, mica powder, aluminum hydroxide, etc.; carbon nanotubes can be used in integrated circuits; metals Lithium is used in the manufacture of lithium batteries; aluminum powder, mica powder, etc. are added to the paint.
Powder materials, powder technology, equipment and operations are used in various industries such as chemicals, plastics, paints, coatings, textiles, building materials, food, electronics, national defense, and environmental protection.
Intensify research efforts in mineral homogenization, purification, ultra-fine grinding, classification and grading, surface modification, etc.; develop in the direction of miniaturization, functionalization, high purification, and refinement; modernization and intelligentization of powder equipment.
Strengthen the application of mineral functional materials in energy saving and fire protection, filling and coating, environmental protection management, energy storage and moisturizing, etc.; extend to the fields of life science and information science.