A Study On Microstructure And Properties Of Ceramic-lined Pipe Made By Centrifugal-SHS

The ceramic-lined pipes, with high quality of resistance to corrosion, heat and wear and excellent property of thermal insulation enable it to have the broad application prospect in many Industry sectors. Centrifugal-SHS opened the new way for ceramic-lined pipe's production. This method use's equipment is also quite simple, saves the energy, the production efficiency is high, the production cost is inexpensive. In this paper, both the history and current situation of the researches on ceramic-lined pipes made by centrifugal-SHS process are generalized. This method existence question and the later development direction are also pointed out, and has forecast in the ceramic-lined pipe broad application prospect.Qianan, Yingtai, Qianda, Daqingzi oil field pipeline, because in corrodes has the corrosion perforation, and the pipeline scaling is serious. The ordinary coating has lost protection. In this situation, decide to replaces steel pipe with ceramic-lined pipes. Because the working conditions are very complex, the pipeline must support each kind of external force and the corrosion, so it is necessary to carries on the test evaluation to the physical mechanical property and inoxidizability of ceramic-lined pipes.In this situation, take ceramic-lined pipes as main object of study, the composition and microstructure of ceramic layer have been analyzed, the influence to physical mechanical property and inoxidizability have been analyzed. Research the physical mechanical property of ceramic-lined pipes, and analyzes its influencing factor. Research the inoxidizability of ceramic-lined pipes while take HCl, H₂SO₄ as the corrosive medium. Analyzes microstructure of ceramic layer that has been corroded, and the corrosion mechanism of materials was researched. Obtains the following conclusion:1. The process of produce ceramic-lined pipes by centrifugal-SHS is through thermit reaction Fe2O3+2Al=2Fe+Al₂O₃+836KJ, the quantity of heat from the reaction causes Al₂O₃ and Fe turns to liquid. Because Al₂O₃ and Fe have different density, so they separated with the centrifugal force. 2. The microstructure was tested by analysis method such as SEM, XRD. The ceramic-lined pipes has three layers, from inside to outside is ceramic layer, metal transition layer, base metal layer. It is metallurgy union between metal transition layer and base metal layer. It is clip type mechanical bond between ceramic layer and metal transition layer. The ceramic layer consists of main crystal phase Al₂O₃ and hercynite spinal phase FeAl₂O₄, Al₂O₃ form the branch-crystal framework in the direction of radial, and FeAl₂O₄ fills up the inner of the Al₂O₃ branch-crystal. The impurities in the ceramic layer are mainly made up of Fe grain, cracks and pores.3. The porosity of the ceramic layer is about 11.98%. The ceramic layer has high hardness 1200-1400 HV, is higher than metal transition layer and base metal layer has. The crushing strength, shear strength, flexural strength has been tested with MTS-810 material testing machine and AG-10TA electronic testing machine. The crushing strength is 430-480MPa, shear strength is 25-28MPa, flexural strength is 105-120MPa. In these test, the ceramic-lined pipe supported big stress, the ceramic layer has high intensity, and has certain bonding strength with base metal. The results show that the ceramic-lined pipe has fine physical mechanical property.4. Study on acid resistance of the ceramic-lined pipe in HCl and H₂SO₄ showed that acid corrosion velocity of the ceramic-lined pipe in varied concentration acid is much less than that of the base pipe in the same condition. The microstructure of ceramic layer that has been corroded was tested by analysis method such as SEM, XRD. The results show that the corrosion mainly extends along the the inner of the Al₂O₃ branch-crystal where the FeAl₂O₄ exist. And the Fe grain, cracks and pores can be the corrosion channel also.