Chemical Degradation Of Ceramics And Polymers 3j3k6t

Chemical Degradation of Ceramics And Polymers

Polymer and Ceramics Degradation - is a change in the properties (tensile strength, color, shape) of a polymer or polymer based product under the influence of one or more environmental factors such as heat, light or chemicals. These changes may be undesirable, such as changes during use, or desirable, as in biodegradation or deliberately lowering the molecular weight of a polymer

Types of Degradation •Physical Degradation -Due to their fragility, damage to ceramics typically comes from mishandling and packing. However, other factors such as vandalism, frost, mold, and other similar occurrences can also inflect harm.[ •Chemical Degradation -The degradation of the chemical component of an object will hinder or weaken the stability of the object when exposed to environmental factors such as water, air, pollution, heat, humidity, and the like.

Radiation Damage

Max Karl Planck - German Physicist. His lifetime spanned the transition between the nineteen and twentieth centuries. This is symbolic of his contribution in bridging classical (nineteenth century) and modern (twentieth century) physics. He introduced the term ‘quantum’ in 1900 while developing a successful model of energy spectrum from a ‘blackbody radiator’.

Effects on Material and Devices Radiation may affect materials and devices in deleterious ways:

•By causing the materials to become radioactive •By nuclear transmutation of the elements within the material including, the production of Hydrogen and Helium which can in turn alter the mechanical properties of the materials and cause swelling and brittleness •By Radiolysis within the material, which can weaken it, cause it to swell, polymerize, promote corrosion, cause belittlements, promote cracking or otherwise change its desirable mechanical, optical, or electronic properties. •By formation of reactive compounds, affecting other materials ( •By ionization causing electrical breakdown, particularly in semiconductor employed in electronic equipment, with subsequent currents introducing operation errors or even permanently damaging the devices.

Effect on Gas • Exposure to radiation causes chemical changes in gases. The least susceptible to damage are noble gas, where the major concern is the nuclear transmutation with follow up chemical reactions of the nuclear reaction products. • Significant amounts of ozone can be produced. Even small amounts of ozone can cause ozone cracking in many polymers over time, in addition to the damage by the radiation itself.

Effect on Liquid • Like gases, liquids lack fixed internal structure; the effects of radiation is therefore mainly limited to radiolysis, altering the chemical composition of the liquids. As with gases, one of the primary mechanisms is formation of free radical.

Wear Degradation • Defined as removal of surface material as a result of mechanical action.

Four Main forms of Wear • ADHESIVE WEAR -occurs when two smooth surface slide over each other and fragments are pulled off one surface and adhere to other. • ABRASIVE WEAR -occurs when a rough, hard surface slides on a softer surface

• SURFACE FATIGUE WEAR -occurs during repeated sliding or rolling over a track. Surface or subsurface crack formation leads to breakup of the surface • CORROSIVE WEAR -takes place with sliding in a corrosive environment and, of course, adds chemical degradation to the physical effects of wear

• EROSION -stream of sharp particles is analogous to abrasive wear. • CAVITATION -involves damage to a surface caused by the collapse of a bubble in an adjacent liquid.

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