Question

Some fisherman prefer keeping ceramic scissors in their tackle box, rather than metal scissors. Provide two advantages ceramic scissors would have over stainless steel one. Justify your answer.

Answer 1

1) Ceramic is Immune to chemical attacks, it is 100% stainless.

The sea/ocean environment is highly corrosive for steels (including stainless steels) due the excessive moisture and presence of various corrosive salts. The name "stainless steel" is actually deceptive in the sense that the steel is not 100% stainless. It is susceptible to chemical attacks over prolonged exposure to corrosive environment. Failure usually starts in the form of Pitting in case of Stainless steels. Exposure over prolonged periods can cause oxidation and rusting of stainless steels which is not desired for handling food items. This also impairs the function of scissors (jamming).

Ceramics, on the other hand, are truly inert and do not react with moisture or salts. Hence Ceramics are 100% stainless. This is due to the chemically inactive composition of ceramics (carbides, silicate, etc) which makes them extremely stable. This also makes ceramics safe for food handling purposes. Their low thermal expansion coefficient also makes them immune to jamming.

2) Ceramics can retain sharpness for a longer time

Steels are inherently ductile in nature. After a certain number of cuts, the sharp edge of stainless steels starts to yield and gradually becomes blunt. This occurs due to plastic deformation of steel under applied loads. Imagine the sharp edge bending inwards, and exposing a blunt edge for cutting with increasing usage.

In ceramics, there is no plastic deformation. Failure occurs only due to fracture/breaking. Thus, the sharpness of the edge is retained for a longer time. Ceramics lose sharpness only by means of microscopic fracture (chipping) of material at localised points. Thus, even after prolonged use, the original sharpness is retained througout most of the cutting edge.

So, what are the downsides of using Ceramic scissors:

1) Cost: They tend to be very expensive

2) Brittle: They are brittle. This means that they can easily break when exposed to shock loads. Like dropping from a certain height. They can be used to cut only soft materials.

3) They can be resharpened only for a limited number of times. With each sharpening cycle, some material is removed. You can only remove so much material without impairing the function of the scissors.