Research On The Performance Of Recycled Carbon Fiber Reinforced Refractory Castable

In recent years,with the increasing application of Carbon fiber reinforced polymer(CFRP)in various fields,a large amount of waste CFRP materials are produced,which brings serious environmental challenges.In order to realize the recycling of composite materials,scholars from various countries have made some achievements in the recycling of waste CFRP.Many different recycling methods have been applied,among which the pyrolysis recycling method is the most widely used.However,the carbon fiber recovered from CFRP waste by pyrolysis recovery method is mostly unglued and disordered fluffy short fiber,which is difficult to reuse and the secondary processing cost is high,so it is necessary to seek a new recycling direction for the recycled carbon fiberWear-resisting steel fiber castable is widely used in metallurgical furnace because of its advantages of high strength and good construction performance.However,due to the increasing temperature required by smelting technology,the life of wear-resisting steel fiber castable is greatly shortened due to repeated rising and cooling,and the steel fiber is prone to oxidation and melting at high temperature,leading to the decline of its mechanical properties.In order to improve this problem,the carbon fiber recovered from waste CFRP will be added to steel fiber refractory castable,the use of carbon fiber high strength,high modulus,has a good crack resistance and toughening characteristics,improve the mechanical properties of steel fiber wear-resistant castable,improve the high temperature melting of steel fiber caused by the problem of castable strength decline.The main research contents and results of this paper are as follows:(1)The SEM,XPS and Zeta potential of recycled carbon fiber and commercial carbon fiber were compared,and the effects of recycled carbon fiber and commercial carbon fiber on the mechanical properties of steel fiber castable were compared.It was found that compared with the commercially available carbon fiber,the regenerated carbon fiber has a fluffier shape,no adhesive on the surface,uniform dispersion between fibers,more oxygencontaining functional groups,greater absolute value of Zeta potential,better dispersion,which plays a better role in enhancing the mechanical properties of castable,and is more suitable to be added into refractory castable as reinforcement material.(2)The effects of different concentrations of CMC dispersing agent on dispersing properties of regenerated carbon fiber were investigated.It was found that the absolute value of Zeta potential of regenerated carbon fiber in 0.3wt%CMC solution was the highest,and no obvious deposition occurred.Four electrode method was used to measure the castable resistance,and it was found that when 0.3wt%CMC was used as dispersant,the castable resistivity was the lowest,indicating that 0.3wt%CMC used as dispersant had the best dispersion effect for regenerating carbon fiber.(3)The effects of different lengths of regenerated carbon fiber on mechanical properties of steel fiber castable at room temperature were investigated.It was found that the mechanical properties of castable were the best when the length of regenerated carbon fiber was 4mm.If the length of carbon fiber is too short,it can not play a good crack resistance and toughening effect.If the length of carbon fiber is too long,it is easy to aggregate and distribute unevenly,which reduces the mechanical properties of castable.(4)The effects of different amounts of recycled carbon fiber on mechanical properties and microstructure of steel fiber castables were investigated.The bulk density and apparent porosity of the steel fiber castable after roasting at 110℃ were the highest.The mechanical properties reached the maximum when the amount of recycled carbon fiber was 0.3wt.%,and the compressive strength and flexural strength were increased by 16% and 62%respectively.After 1100℃ treatment,carbon fiber in castable oxidized greatly,resulting in the lowest strength of castable.The mechanical properties of steel fiber castables after heat treatment at 1100℃ and 1450℃ reached the maximum when the content of carbon fiber was 0.25 wt.%,and the compressive strength and flexural strength increased by 26% and28%,respectively,and 36% and 57%,respectively.(5)The effects of Si powder addition on mechanical properties,microstructure and oxidation resistance of castable were investigated.With the increase of Si powder,the volume density,compressive strength and flexural strength of recycled carbon fiber reinforced steel fiber castable increased,and the apparent porosity decreased.When 3w.%Si powder was added,Si Ox microspheres and Si C whiskers formed on the surface of carbon fiber after heat treatment at 1100℃,which protected the regenerated carbon fiber,reduced the apparent porosity of castable,and significantly improved the mechanical properties.After heat treatment at 1450℃,a large number of Si C whiskers were generated on the surface of the regenerated carbon fibers at high temperature,which played an anti-oxidation protection role on carbon fibers and formed an interlocking structure,which greatly improved the mechanical properties of castables.