超音速火焰喷涂制备铁基非晶合金涂层的研究现状

A State-of-the-art Review of Fe-based Amorphous Alloy Coatings Prepared by High-velocity Oxygen Fuel Spray Process

非晶合金的短程有序,长程无序和不存在晶界、位错等晶体缺陷等特点,使其具有较高的强度以及优异的防腐耐磨性能,从而成为一种具有广阔应用前景的新型金属材料。然而,由于非晶合金体系本身非晶形成能力和制备技术的限制,目前难以得到具有工程意义的大尺寸块体结构材料。为了充分利用其优异的性能和扩大其应用领域,众多学者对制备非晶合金涂层展开了广泛研究。以超音速火焰喷涂为代表的热喷涂技术由于具有加工工艺简单、热输入低、喷涂材料范围大、制备的涂层耐磨耐蚀性能好等优势成为了制备非晶合金的重要方式。目前,利用超音速火焰喷涂技术制备的非晶合金涂层主要有Fe基、Ni基和Mo基等。而在众多的非晶体系中,Fe基非晶合金涂层由于其优异的性能和低廉的成本受到了广泛关注。研究者们发现,制备性能优异的Fe基非晶合金涂层不仅需要合适的制备方法,同时合金系成分的合理选择以及制备过程中工艺参数的优化能够完善非晶合金本身的优良特性,保证非晶合金具有更好的非晶形成能力并提高涂层的质量及使用性能。目前,通过超音速火焰喷涂的涂层孔隙度通常低于2%,在使用改进型空气超音速火焰喷涂系统后可以将涂层的孔隙度降低到0.3%以内,使得涂层更致密,减少涂层浸泡在腐蚀介质中由于孔隙造成的涂层破坏,延长涂层的使用寿命。另外,在深共晶规律、电子密度规律、热力学规律等经验规律的指导下,研究者们开发了很多成分多元的Fe基合金体系,使得制备的非晶合金涂层在耐磨耐蚀等性能上都有很大提升,例如七元合金体系中的Fe_(40)Cu_8Cr_(15)Mo_(14)C_(15)B_6Y_2在干摩擦磨损实验中,磨损量仅为相同条件下45号钢的四分之一,说明其具有优异的耐磨性能;八元合金体系中的Fe_(6.3)Cr_sMo_(3.5)Ni_5P_(10)B_4C_4Si_(2.5)在进行3.5%(质量分数)NaCl溶液的电化学腐蚀实验后,比相同条件下304不锈钢涂层表面的腐蚀坑更少、更小,拥有更好的抗腐蚀性能。本文对超音速火焰喷涂Fe基非晶合金的研究现状进行了综述,归纳总结了合金化学成分和喷涂参数对Fe基非晶合金涂层摩擦学性能和耐蚀性能的影响。并对超音速火焰喷涂制备性能优异的Fe基非晶合金涂层的研究前景进行了展望。

Amorphous alloy features short-range order and long-range disorder of atomic arrangement,no crystal defects like grain boundaries or dislocations,which ensure its superior performance of high strength,excellent corrosion and wear resistant compared to any other crystal materials.Therefore,amorphous alloy turns out to be an innovative metal material with wide application prospects.Nevertheless,the limitations of the glass forming ability and preparation technologies of amorphous alloy systems make it difficult to obtain large-scale bulk structural materials for engineering applications.Aiming at taking full advantage of the excellent pro-perties and expanding the application range of amorphous alloys,extensive research efforts have been put into the preparation of amorphous alloy coatings.The thermal spraying technology represented by high velocity oxygen fuel has become the major method for preparing amorphous alloys,thanks to simple processing technology,low heat input,large range of spray materials,and good wear and corrosion resistance of the prepared coatings.At present,amorphous alloy coatings prepared by high velocity oxygen fuel technology mainly include Fe-based,Ni-based,Mo-based and other systems.Among these amorphous alloy systems,Fe-based amorphous alloy coatings have raised great concern due to their excellent properties and low cost.It has been found that achieving Fe-based amorphous alloy coatings with satisfactory properties requires not only appropriate preparation methods,but also reasonable selection of alloy compositions and optimization of process parameters,which can enhance the excellent properties of the amorphous alloys themselves,and further ensure the better amorphous forming ability,quality and performance of the coatings.At present,the porosity of coatings prepared by high velocity oxygen fuel is usually less than 2%.The modified high velocity air fuel technology is able to reduce the porosity of the coating to less than 0.3%,and make the coatings denser.It will also reduce the damage caused by the corrosion of pores when immersed in the corrosive medium and prolong the service life of the coatings.Besides,with the guidance of deep eutectic law,electron density rule,thermodynamic laws and other empirical rules,the researchers have developed plenty of Fe-based alloy systems,which greatly improve the wear and corrosion resistance of the prepared amorphous alloy coating.For example,Fe 40 Cu 8Cr 15 Mo 14 C 15 B 6Y 2,the seven-element alloy system,shows excellent wear resistance performance that it presents only 1/4 wear loss of the AISI 1045 steel under the same conditions in the dry friction wear test.The eight-element alloy system Fe 63 Cr 8Mo 3.5 Ni 5P 10 B 4C 4Si 2.5 exhibits less and smaller corrosion pits compared to 304 stainless steel in the electrochemical corrosion test in 3.5wt%NaCl solution under the same conditions,showing better corrosion resistance performance.In this article,a state-of-the-art review on Fe-based amorphous alloy coatings prepared by high velocity oxygen fuel technology is given.The effects of chemical composition and parameters of spraying processing on the wear and corrosion resistance performance of Fe-based amorphous alloy coatings are summarized.Meanwhile,the research prospects of Fe-based amorphous alloy coating with favorable performance prepared by high velocity oxygen fuel technology are also proposed.