Kimia Bahan Bangunan

Kimia Bahan BangunanHamzah Fansuri, Ph.D1MateriSemenKeramikGelasLogamAksesorihttp://en.wikipedia.org/wiki/Building_materials10 Maret 2009

4. LogamLogam memiliki konduktivitas panas dan listrik yang tinggi, berkilau, berkerapatan tinggi dan dapat diubah bentuknya tanpa harus memutus ikatan kimianya. DensityMalleability/lunak: Dapat ditempa (ductile)The nondirectional nature of metallic bonding is thought to be the primary reason for the malleability of metal. Planes of atoms in a metal are able to slide across one another under stress, accounting for the ability of a crystal to deform without shattering.ConductivityElectric charge

http://www.onelargeprawn.co.za/wp-content/uploads/2009/osaka.jpgSteel (Baja)Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight (C:11010Fe). Various other alloying elements are used too such as Mn, Cr, V, and W. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another.

Steel with increased carbon content can be made harder and stronger than iron, but is also more brittle. The maximum solubility of carbon in iron (as austenite) is 2.14% by weight, occurring at 1149 C; higher concentrations of carbon or lower temperatures will produce cementite. Alloys with higher carbon content than this are known as cast iron because of their lower melting point and castability.

Wrought iron containing only a very small amount of other elements, but containing 13% by weight of slag in the form of particles elongated in one direction, giving the iron a characteristic grain. It is more rust-resistant than steel and welds more easily.

Fasa-fasa BajaIron alloy phases vdeFerrite (-iron, -iron; soft)Austenite (-iron; harder)SpheroiditePearlite (88% ferrite, 12% cementite)BainiteMartensiteLedeburite (ferrite-cementite eutectic, 4.3% carbon)Cementite (iron carbide, Fe3C; hardest)Steel classes Carbon steel (2.1% carbon; low alloy)Stainless steel (+chromium)Maraging steel (+nickel)Alloy steel (hard)Tool steel (harder)

Other iron-based materials Cast iron (>2.1% carbon)Ductile ironWrought iron (contains slag)

AluminiumMost widely used non-ferrous metal.

Global production: 31.9 million tonnes (iron: 837.5 million tonnes). Pure aluminium is encountered only when corrosion resistance and/or workability is more important than strength or hardness.

A fresh, pure aluminium film serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) of medium and far infrared.

Aluminium alloys display a marked improvement in mechanical properties, especially when tempered and have high strength-to-weight ratio.

Aluminium readily forms alloys with many elements such as copper, zinc, magnesium, manganese and silicon (e.g., duralumin).

http://www.c-a-b.org.uk/images/home/9.jpgAluminium AlloyAluminium alloys with a wide range of properties are used in engineering structures. Alloy systems are classified by a number system (ANSI) or by names indicating their main alloying constituents (DIN and ISO).

The strength and durability of aluminium alloys vary widely. A lack of knowledge of these aspects has from time to time led to improperly designed structures and gained aluminium a bad reputation.

One important structural limitation of aluminium alloys is their fatigue strength. Unlike steels, aluminium alloys have no well-defined fatigue limit, meaning that fatigue failure will eventually occur under even very small cyclic loadings. This implies that engineers must assess these loads and design for a fixed life rather than an infinite life.

Sensitivity to heat. Workshop procedures involving heating are complicated by the fact that aluminium, unlike steel, will melt without first glowing red. F

Aluminium alloys are subject to internal stresses following heating operations such as welding and casting. The problem with aluminium alloys in this regard is their low melting point, which make them more susceptible to distortions from thermally induced stress relief. Controlled stress relief can be done during manufacturing by heat-treating the parts in an oven, followed by gradual cooling -- in effect annealing the stresses.Logam-logam lainTembagaPerungguEmasPlatinaSengTitaniumTugas (4 jam kerja/2SKS)Steel classes Carbon steel (2.1% carbon; low alloy)Stainless steel (+chromium)Maraging steel (+nickel)Alloy steel (hard)Tool steel (harder)Aplikasi Alloy aluminium sebagai bahan bagnunan (contoh dan sifat)