Cohesional Strength
Bond strength refers to the bonding force between the unit interfaces when the two materials are bonded together. The bond strength of refractories is mainly characterized by the strength index of amorphous refractories at various temperatures and specific conditions. When the amorphous refractory is used, it should have a certain bonding ability so that it can be effectively bonded to the construction matrix. The bond strength of refractories is usually characterized by bending bond strength or shear bond strength. The bending bond strength of specimens coated with mud is the maximum stress that the bond surface of specimens coated with mud can bear when bending in a three-point bending device, while the shear bond strength can be borne by specimens coated with mud. The ratio of the maximum shear force to the bond area of the specimen is the ultimate average shear stress of the bonding surface.
The black metallurgical industry standard YB/T5123-1993 specifies the test method of refractory mud cold state flexural bond strength. The main point of the test is that the refractory brick test block is bonded to a parallel hexahedron sample of a certain size with the refractory mud for test, and the bending stress is applied to the bond surface of the sample at a constant rate at room temperature after drying and roasting until the bond surface is broken.
The bending bond strength is calculated according to the following formula:
R=3FL/2bh2
In the formula R = bending bond strength, MPa;
F = the maximum load of the specimen when the bond surface is broken, N;
L = the center distance between the two bearing shafts, mm;
B = width of specimen at bonding surface, mm;
H = height of specimen at bonding surface, mm.
The black metallurgical industry standard YB/T 5163 / 1993 specifies the test method for hot bending strength of refractory mud. The main point of the test is that the refractory brick test block is bonded into a cuboid test block of a certain size with refractory mud for test. After drying, the refractory brick test block is heated to the test temperature at a specified heating rate for a certain time, and then the bending stress is applied to the bond surface of the test block at a constant loading rate until the bonding surface breaks.
The thermal bending bond strength is calculated according to the lower formula.
R heat = 3FL/2bh2
R heat = thermal bending bond strength, MPa;
F = the maximum load of the specimen when the bond surface is broken, N;
L = the distance between the lower edges of the knife, mm;
B = width of specimen at bonding surface, mm;
H = height of specimen at bonding surface, mm.
The black metallurgical industry standard YB/T 5123 / 1993 specifies the cold shear bond strength test method of refractory mud. The key point is that the refractory brick test block is bonded with refractory mud for test. After drying or calcination, the shear test is carried out at room temperature until the bonding surface breaks.
The shear bond strength is calculated according to the following formula:
BS=F/A
The shear bond strength of BS= is N ≤ cm2;
F = the maximum load of the specimen when the bond surface is broken, N;
A = bond area of specimen, cm2.