Hardness. Hardness - the resistance of the surface layers of material to local deformation. Usually, it is estimated resistance vdavlmnaiiyu indicator (ball, cone, etc.).There is also the hardness scale, the proposed MEP and named after him. This scale is composed of a number of materials which are to increase the hardness, with each successive scratch the previous one. In this scale, each mineral has its own number, which characterizes its relative hardness. The hardest of them - diamond - has the number 10, corundum-№ 9. The hardness of all other materials evaluated in comparison with the hardness of the ten standard minerals. Glass depending on its composition) on the Mohs scale of hardness has a 5-7, ie, it is very solid.
The hardest are quartz glass and Pyrex-type glass.
Compressive strength and tensile. Strength - the resistance of the material destruction. It is characterized by tensile strength, which is determined by the least amount of effort involved per unit area, causing destruction of the material. In CGS units, this value is measured in dynes per square centimeter (dynes/cm2) in SI units - in pascals (Pa): 1 dyn/cm2 = 0.1 Pa.
Compressive strength is determined by the force of compression, tensile strength - the power to stretch.
Glass fairly durable material, and its strength depends on the composition and processing method. Compressive strength of glasses of different species is in the range of 5 to 200 kg/mm2, ie, from before 1,9-10 19,6-10 dnn/sm2 or 4,9-108 - 19,6-10 kPa. To understand how resistant glass can cause shachenie to compare the compressive strength of cast iron 60 ~ 120 kg/mm2 (ie,. 88-109 dyn/cm2 5,88-10 11,76-10 ~ * 4 - 11.76-10e Pa) and were 200 kg/mm2 (19,6-109 dynes/cm2 = 19.6 - 10 Pa).
Tensile strength of glass under tension in 15 20 times smaller than the compressive strength and makes 3,5-10 kg/mm2 (3.43-108-m-9,8-108 dnn/sm2 = 3.43 - 107 ~ 9 8-10,7 Pa).
Flexural strength. When bending glass, and experiences a tensile and compressive forces. Strength of Glass Flexure determined by putting the free end of a glass rod on two supports and gradually increasing the load in the middle of it up to the failure of the rod. Strength of Glass Flexure lower tensile strength (10 ~ 25 kg/cm2), so sites in places bends tubes and oglelkn bottom pieces (shoulders) should be thickened.