Method for measuring shear strength of machinable ceramics

A technology of shear strength and ceramics, which is applied in the direction of testing material strength by applying stable shear force and testing material strength by applying stable tension/compression, which can solve the problem of stress concentration and homogeneous ceramic shear strength. Methods and other issues to achieve the effect of avoiding stress concentration, solving evaluation difficulties, and making sample preparation easy

Inactive Publication Date: 2005-03-30
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

It has been found that shear-induced failure is the main failure mechanism of this type of ceramics, but how to accurately evaluate the shear strength has not been fully resolved
Although double-notch specimens, four-point bending, and the newly developed cross-type specimens are often us

Method used

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  • Method for measuring shear strength of machinable ceramics
  • Method for measuring shear strength of machinable ceramics
  • Method for measuring shear strength of machinable ceramics

Examples

Experimental program
Comparison scheme
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Example Embodiment

[0032] Example 1: The thickness effect of the punching method

[0033] One advantage of the indentation shear test is that simple flake samples without shape requirements can produce a series of experimental results, and the indentation shows a good shape without crack branches. figure 2 The sample with the punched hole and the punched disc are displayed. The one marked "A" is punching, and the one marked "B" is punching disc. figure 2 It also shows the shear failure without ejecting the wafer, marked as "C". The small disk "C" embedded in the sample has no obvious concave surface, indicating brittle failure with small shear strain. Shear strength is generally regarded as a material constant. Therefore, in formula (1), the ratio of critical load to sample thickness Pc / h should also be a constant.

[0034] Pc=C·h h≤hc (2)

[0035] Here C is a constant. However, experiments show that this proportional relationship is only valid when the thickness of the sample is lo...

Example Embodiment

[0039] Example 2: Effect of loading rate and punch diameter

[0040] In the indentation shear test, various loading rates were applied to 0.24mm thick Ti 3 AlC 2 The results of plate-shaped sample experiments show that the loading rate has little effect on the experimental results. Figure 7 It shows that the shear strength measured at various punch speeds from 0.05mm / min to 5mm / min is basically at the same level. The reason may be that the machinable ceramic has a slow subcritical crack growth rate, so it is not sensitive to the loading rate.

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Abstract

The method for testing shearing strength of workable ceramics includes 1). using linear cutting process to cut out thin plate samples with various thickness from large block of sintered sample, then polishing them; 2). fixing plate sample between hard steel grippers, centres of upper and lower two grippers are opposite and a through hole through which a hard column punching head can be frictionlessly passed is cut; 3) adopting general material test machine to press hole and using thin plate sample whose relative thickness h/d=0.07-0.1 to determine shearing strength of ternary layer workale ceramics; and 4). using critical load and shearing zone area to calculate shearing strength. Said method is called hole-pressing method, its reliability is strong and operation is simple.

Description

technical field [0001] The invention relates to the shear strength test of machinable ceramics, in particular to a method for testing the shear strength of machinable ceramics and effectively evaluating it. Background technique [0002] Usually, the failure of materials under complex stress is controlled by the weakest stress. Therefore, the weakest ability of materials to hinder fracture is very important for safety design and reliability analysis. Ternary layered machinable ceramics is a new type of material that combines the excellent properties of metals and ceramics. This material has similar advantages: high elastic modulus and toughness, low hardness, metal electrical conductivity, excellent thermal shock performance, high damage tolerance and good processability, which are attributed to its unique crystal lattice and electronic structure. It has been found that shear-induced failure is the main failure mechanism of this type of ceramics, but how to accurately evalu...

Claims

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Application Information

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IPC IPC(8): G01N3/08G01N3/24
Inventor 包亦望周延春
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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