compressive strength of cast iron as compared to tensile strength
Cast iron The earliest cast-iron artifacts date to the 5th century BC, and were discovered by archaeologists in what is now modern Luhe County, Jiangsu in China. This is based on an analysis of the artifact's microstructures.[2] Because cast iron is comparatively brittle, it is not suitable for purposes where a sharp edge or flexibility is required. It is strong under compression, but not under tension. Cast iron was invented in China in the 5th century BC and poured into moulds to make ploughshares and pots as well as weapons and pagodas.[11] Although steel was more desirable, cast iron was cheaper and thus was more commonly used for implements in ancient China, while wrought iron or steel was used for weapons.[2]
Bone china The production of bone china is similar to porcelain, except that more care is needed because of its lower plasticity and a narrower vitrification range. The traditional formulation for bone china is about 25% kaolin, 25% Cornish stone and 50% bone ash.[11] The bone ash that is used in bone china is made from cattle bones that have a lower iron content. These bones are crushed before being degelatinised and then calcined at up to 1250 °C to produce bone ash.[12] The ash is milled to a fine particle size.[13] The kaolin component of the body is needed to give the unfired body plasticity which allows articles to be shaped.[2] This mixture is then fired at around 1200 °C.[13] The raw materials for bone china are comparatively expensive, and the production is labour-intensive, which is why bone china maintains a luxury status and high pricing.[5]