Chemical Elements That Make Up A Substance

The reserves of Zr in the earth's crust are 0.025%, exceeding the reserves of metals such as Cu, Zn, Sn, Ni, and Pb, and the resources are abundant.

rich. In nature, Zr appears in the form of zircon, baddeleyite and their variants.

High-purity Zr0₂ is white powder, yellow or gray when it contains impurities, generally contains HfO₂, not easy to separate, melting point 2715°C. At different temperatures, ZrO₂ mainly exists in three isomorphic forms, namely monoclinic (m-Zro₂).

The tetragonal crystal system (t-ZrO₂) and the cubic crystal system (c-ZrO₂), the schematic diagram of the crystal structure is shown in Figure 1-1.

The chemical compositions of the three structures of Zr0₂ are basically the same, and their existing forms are related to temperature and pressure, At normal pressure, the relationship among the three forms can be expressed as:

However, when appropriate stabilizers, such as Y₂O₃, Mgo, CaO, CeO₂, etc. are added to ZrO₂ ceramics, the cubic phase (c)--tetragonal phase (t) and tetragonal phase (t)--monoclinic phase (m) can be reduced. The phase transition temperature enables the high temperature stable cubic and tetragonal phases to be stable or metastable at room temperature. When enough stabilizer is added, the cubic phase stable at high temperature can be maintained until room temperature without phase transition.
Y-TZP:Yttria Stabilized Zirconia Bead
CZ:Ceria Stabilized Zirconia Bead

The true density is that the object is dried to a constant weight under the specified conditions (105 degrees plus or minus 5 degrees, and the temperature is 20 degree plus or minus 2 degrees), the mass per unit true volume (the volume of the mineral entity without pores)

ρ=m/v

Detection method: According to Archimedes' law, the real volume of the object is measured by the drainage method.

In the natural state of accumulation, the bulk volume of the material includes the internal pores of the material and the loose material particles mass per unit volume of pores between

ρ=m/V

Heap specific gravity detection

Detection equipment: 100ml volumetric flask, electronic balance

Detection method:

a. Pour the detected ball into a 100ml volumetric flask, and pour it on the scale accurately.

b. Weighing G

c. Calculation formula:

Bulk specific gravity D=G/100

Bulk Specific Gravity of Grinding Media for Various Materials

Formula: W=P*D*L

P---Filling rate

D---Heap specific gravity

L---Effective use volume

Hardness indicates the ability of a material to resist the pressing of a hard object into its surface. it is metal

One of the important performance indicators. Generally speaking, the higher the hardness, the better the wear resistance. commonly used hardness

The indicators are Brinell hardness (HB), Rockwell hardness (HR), Mohs hardness and Vickers hardness (HV).

Strength is the ability of a material to resist damage. But often under different stress conditions, the strength exhibited by the material is different. Under compressive stress, resistance to damage. is the compressive strength.

When the material sample is under pressure, the maximum stress that it will bear before crushing Unit: MPa or N/mm2

The water absorption rate is the percentage of the water absorbed by the pores in the ceramic product.

Porosity is the percentage of pores in a ceramic article that account for the total volume of the article.

A.Sieve

The operation of classifying solid particles into several levels by size is called classification, using

The grading of a screen surface with a certain size of aperture is called sieving.

B.Mesh

Chinese standard sieve adopts metric sieve size

The sieve size is expressed by the number of sieve holes per square centimeter area, and the sieve number is expressed by the number of sieve holes on one centimeter of length

Imperial sieve number

The number of holes n per inch of length

The number of meshes counted in a row on a given unit length in succession.

Note: The number of meshes with a length of 25.4mm, that is, marked "mesh".

1 inch = 25.4mm

Amount of loss per unit time of grinding media during use

Testing equipment: fast mill, 1L ball mill, slow mill, 4L ball mill, electronic balance

Detection method: 1) Rapid grinding (aluminum powder)

1) Rapid grinding (aluminum powder)

a. Use an electronic balance to weigh about 800 grams of ball G1, 100 grams of alumina powder, 380 grams of water

Put it into a 1L ball mill jar and quickly grind it for 6 hours

b. Cleaning, drying and weighing G2.

Calculation formula:

Wear W=(G1-G2)/G1*100%

2) Slow grinding,

a. Use an electronic balance to weigh about 2500 grams of the ball and weigh G1, put 2500 grams of water into a 4L ball mill, and mill it for 60 hours.

b. Cleaning, drying and weighing G2.

Calculation formula:

Wear W=(G1-G2)/G1*100%

Wear is mainly divided into four basic types according to different mechanisms and conditions:

①Adhesive wear, the main feature is that there are fine scratches on the wear surface, and material transfer phenomenon occurs in severe cases, and the wear products are mostly flakes or small particles;

②Abrasive wear, the main feature is that there are obvious scratches or furrows on the wear surface, and the wear objects are strips or cuttings;

③Fatigue wear, the main feature is that there are cracks, small pits, etc. on the wear surface, and the wear products are block or cake;

④Corrosion wear, the main feature is that there are chemical reaction films or small pits on the worn surface, but the pits are relatively smooth.