微束等离子喷涂制备羟基磷灰石涂层微观结构的特征研究

目的 通过与大气等离子喷涂和超音速火焰啧涂的对比,研究微束等离子喷涂制备的羟基磷灰石涂层的微观组织特点.方法 以高结晶度的羟基磷灰石粉末为原料,采用三种不同的喷涂方法(微束等离子喷涂、大气等离子喷涂和超音速火焰喷涂),在Ti-6Al-4V基体上制备羟基磷灰石(HA)涂层.利用冷场发射扫描电子显微镜和X射线衍射仪,对三种涂层的形貌、相组成和择优取向进行分析.结果 与大气等离子喷涂及超音速火焰喷涂制备的涂层相比,应用该设备制备的羟基磷灰石涂层表面平整致密,无大量的气孔存在;涂层截面呈典型的层状结构,在近三分之一表面处观察到柱状晶;涂层中仅有少量的非晶相及分解相,结晶度高达90％以上.这些特征均有利于羟基磷灰石涂层在体液环境中的稳定性.结论 比较三种喷涂方法,采用微束等离子喷涂制备的羟基磷灰石涂层致密,结晶度高,杂相少,且存在择优取向的柱状晶.     

热处理对微束等离子喷涂羟基磷灰石涂层的影响

羟基磷灰石由于其良好的生物活性,被广泛的用作医用植入体的表面涂层材料.采用微束等离子喷涂(Microplasma Spraying,MPS)I艺在Ti-6Al-4V基体上制备羟基磷灰石涂层,通过扫描电镜(SEM)、X射线衍射(XRD)和傅里叶红外光谱(FTIR)分析了热处理对涂层相组成和表面形貌的影响规律.研究表明:微束等离子喷涂制备的羟基磷灰石涂层在经过热处理后结晶度提高,并且非晶相和杂质相转化成为HA结晶相.同时,羟基和磷酸根的完整性得到了恢复.过高的热处理温度易引起涂层裂纹等缺陷的增加,也容易造成羟基脱离造成HA分解.合理的热处理温度范围为600～700℃,保温时间为3 h.     

微束等离子喷涂羟基磷灰石涂层的体外生物活性研究

采用微束等离子喷涂(MPS)方法在Ti6A14V基体上制备羟基磷灰石(HA)涂层.利用扫描电镜(SEM)和x射线衍射(XRD)分析技术对HA涂层的表面形貌、相组成和结晶度进行表征,并通过模拟体液进行体外生物活性试验.结果表明,微束等离子喷涂制备的HA涂层具有一定粗糙度,存在气孔以及微裂纹.涂层存在热分解现象,涂层中含有HA、α-TCP、β-TCP和非晶相,不含CaO等杂质相.模拟体液试验表明,微束等离子喷涂工艺制备的HA涂层具有较好的生物活性和稳定性.涂层表面均有较大比例的CaP沉积层,且涂层整体保持完整,没有出现明显的剥离.     

微束等离子喷涂氧化锆增韧羟基磷灰石复合涂层

采用微束等离子喷涂方法,在Ti-6Al-4V基体上制备了羟基磷灰石 氧化锆(70HA-30ZrO2,质量分数,%)复合涂层.将复合涂层置于模拟体液中分别浸泡了3,7,14,28 d并观察表面磷灰石的生长情况以评价涂层生物活性.采用扫描电镜(SEM)和X射线衍射(XRD)分析技术对涂层浸泡前后的表面形貌和相组成进行了研究.结果表明,涂层中ZrO2主要以立方相存在;喷涂过程中羟基磷灰石(HA)出现了一定的分解,产生大量的α-Ca3(PO4)2杂质相.HA涂层熔化效果很好,但涂层中有未熔化的ZrO2颗粒.涂层在模拟体液中浸泡28 d后表面可以形成磷灰石,说明涂层具有很好的生物活性.     

HA粉末粒径对微束等离子喷涂扁平粒子形貌及涂层微结构的影响

目的研究粉末粒径对微束等离子喷涂羟基磷灰石(HA)扁平粒子形貌和涂层的微观组织结构的影响。方法选取三组不同粒径范围(25～38μm、38～45μm、45～63μm)HA球形粉末,采用微束等离子喷涂方法在经镜面抛光的Ti-6Al-4V基体上收集扁平粒子,在经过喷砂处理的Ti-6Al-4V基体上沉积HA涂层。利用冷场发射扫描电子显微镜和X射线衍射仪,对扁平粒子形貌,以及涂层的形貌、相组成和择优取向进行分析。通过激光共聚焦显微镜(LSCM)观察扁平粒子的三维相貌,并对比分析扁平粒子的差异。结果微束等离子喷涂过程中,可形成几种典型形貌特征的扁平粒子,一是中间区域较厚,边缘位置较薄的扁球形;二是中间区域较薄,边缘位置较厚的圆盘状,该种扁平粒子相比于扁球形,其厚度较薄,直径较大;三是边缘位置存在"指状"溅射的圆盘状,其厚度与圆盘状扁平粒子厚度相当,但其直径范围较大。HA涂层的结晶度随着粉末粒径的减小而减小,HA的分解和非晶化逐渐增强,涂层的择优取向强度减弱,涂层中柱状晶比例减少。结论微束等离子喷涂过程中,粉末粒径对扁平粒子形貌和涂层相结构有显著影响。随着粒径的增加,扁平粒子由扁球形转变为边缘有少量"指状"溅射的圆盘状。粒径较小的HA粉末在等离子焰流中的熔化程度较高,导致涂层中分解相和非晶相含量增多,择优取向程度减小。     

微束等离子喷涂气体对HA涂层结晶度的影响

采用微束等离子喷涂方法,分别选用工业纯氩气和含50%氦气的氦氩混合气体为工作气体,在Ti-6Al-4V基体上制备羟基磷灰石涂层.通过SEM和XRD对涂层形貌、相组成和结晶度进行研究.结果表明,两种工作气体均可以制备杂质相含量少且不产生TTCP(磷酸四钙)和CaO等杂质相的涂层,结晶度高于70%,对植入体在体内的稳定性有利.采用氦氩混合气体为工作气体的微束等离子弧热焓值高于氩气工作气体,前者涂层中的结晶相主要以再结晶的为主,后者结晶相以大量未熔HA内核为主.     

金属喷涂、堆焊与修复——金属喷涂工艺与设备

高速电弧喷涂雾化过程的数值模拟,等离子喷涂ZrO2热障涂层的抗热震性能研究,用于加热辊的TiO2＋40％Al2O3陶瓷加热涂层,微束等离子喷涂羟基磷灰石涂层的体外生物活性研究,等离子喷涂过程中粒子的氧化及其对涂层性能的影响……     

钛合金表面生物陶瓷覆层的制备

用CaHPO4·2H2O和CaCO3制备羟基磷灰石粉末,以钛合金Ti6A14V为基材,采用等离子喷涂在不同喷涂距离和喷涂功率下制备羟基磷灰石涂层.结果表明:(1)随着喷涂功率的提高,颗粒的熔化程度提高,涂层与基体的结合强度增强;但同时涂层中的分解程度增加,出现了Ca4(PO4)3等第二相和杂相;增大喷涂距离可使涂层非晶化增强.(2)添加稀土元素可改善涂层的组织结构和界面的结合状况,并且有利于获得细小的晶粒.     

水蒸气处理对钛合金表面羟基磷灰石涂层结构的影响

目的 制备结晶度较高且裂纹较少的羟基磷灰石涂层。方法 采用等离子喷涂法,在不同功率下,于钛合金表面制备羟基磷灰石涂层。通过水蒸气处理法,在不同温度下处理羟基磷灰石涂层。使用扫描电子显微镜（SEM）和X射线衍射仪（XRD）分析羟基磷灰石的表面形貌和晶体结构。结果 当等离子喷涂功率从20 kW增大到29 kW时,羟基磷灰石涂层的沉积效率先增大后稳定,涂层结晶度先增大后减小,涂层中氧化钙的含量先增大后稳定。当喷涂功率为23 kW时,羟基磷灰石涂层结晶度较高。水蒸气处理能明显去除涂层中的α-磷酸三钙、β-磷酸三钙和氧化钙,当水蒸气处理温度从140 ℃增大到200 ℃时,羟基磷灰石涂层晶粒由棒状向颗粒状转变,涂层结晶度不断增大,涂层中磷酸四钙的含量先减小后增大,较高的温度会造成涂层表面微裂纹的产生。在模拟体液中浸泡后,经过水蒸气处理的涂层表面会诱导生成较纯的羟基磷灰石。180 ℃水蒸气处理后的涂层表面会沉积一层均匀的羟基磷灰石,生物活性较高。结论 羟基磷灰石涂层的结晶度随等离子喷涂功率的增大,先增大后减小,随水蒸气处理温度的上升而增大。在合适条件下制得的羟基磷灰石涂层具有较高的生物活性。     

微束等离子喷涂NiCrBSi涂层

采用微束等离子喷涂方法在St37低碳钢上制备了NiCrBSi涂层.研究了基材温度、等离子气体流量、喷涂距离和电流强度等工艺参数对涂层组织结构和性能的影响.采用光学显微镜观察涂层的组织结构,用Perthometers M4P 150测定涂层的表面粗糙度,以及用LECO TC316气体抽提仪检测涂层的氧含量.结果表明,在试验条件下,喷涂参数对涂层组织和性能产生较大的影响.随着电流和基材温度的增加涂层的粗糙度降低,涂层的氧含量随着基材温度和喷涂距离的增加而增加.大多数涂层的显微硬度大于600 HV0.2.尽管粒子速度较低,涂层的平均结合强度仍然大于50 MPa.     

The Influence of Spray Parameters on the Characteristics of Hydroxyapatite In-Flight Particles,Splats and Coatings by Micro-plasma Spraying

Hydroxyapatite (HA) is one of the most important bioceramic materials used in medical implants. The structure of HA coatings is closely related to their manufacturing process. In the present study, HA coatings were deposited on Ti-6Al-4V substrate by micro-plasma spraying. Results show that three distinct HA coatings could be obtained by changing the spraying power from 0.5 to 1.0 kW and spraying stand-off distance from 60 to 110 mm: (1) high crystallinity (93.3%) coatings with porous structure, (2) high crystallinity coatings (86%) with columnar structure, (3) higher amorphous calcium phosphate (ACP, 50%) coatings with dense structure. The in-flight particles melting state and splat topography was analyzed to better understand the formation mechanism of three distinct HA coatings. Results show that HA coatings sprayed at low spraying power and short stand-off distance exhibit high crystallinity and porosity is attributed to the presence of partially melted particles. High crystallinity HA coatings with (002) crystallographic texture could be deposited due to the complete melting of the in-flight particles and low cooling rate of the disk shape splats under higher spraying power and shorter SOD. However, splashed shape splats with relative high cooling can be provided by increasing SOD, which leads to the formation of ACP.     

电弧电压对低能等离子喷涂WC-Co涂层组织及性能的影响

使用烧结破碎的WC-12%Co粉末,采用轴向送粉等离子喷涂系统制备WC-Co涂层。保持电弧电流不变,增加工作气体中的氢气含量来提高电弧电压,以研究电弧电压对于涂层微观结构的影响。使用X射线衍射仪(XRD)分析WC-Co涂层的脱碳相变,使用扫描电子显微镜(SEM)观察粉末的熔化程度、扁平化状态和涂层的微观结构,使用MH-6维氏硬度计和MM200磨损试验机分别测量了涂层的显微硬度和耐磨性。结果表明,提高电弧电压有利于粉末的熔化。根据熔化程度的不同,粉末会呈现四种典型的扁平化状态。提高电弧电压促使碳化钨脱碳生成的W_2C和Co_3W_9C_4,涂层中硬质相体积增加,钴基体积减小。适当提高电弧电压有利于增加涂层的硬度和耐磨性,但过高的电弧电压会恶化涂层质量,反而降低涂层的硬度和耐磨性。     

The effect of plasma spraying power on the structure and mechanical properties of hydroxyapatite deposited onto carbon/carbon composites

This paper deals with the effect of plasma spraying power on hydroxyapatite (HA) coatings on carbon/carbon composites (C/C composites). The microstructure and phase composition of the as-sprayed coatings have been examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The shear strength of the HA coatings–C/C substrates was detected on a RGD-5 tensile testing machine. Results indicate that the melting extent and the shear strength of the coatings were evidently improved with the increasing of spraying power. Moreover, the amount of decomposed phases is increased and the content of crystalline HA of coatings was slightly changed. Observation of fracture surfaces shows that carbon fiber bundles can bond well with HA coatings using 40 kW spraying power.     

前驱体溶液等离子喷涂参数对涂层形貌的影响及沉积行为机理研究

目的对不同喷涂工艺参数下涂层的相结构、显微形貌进行研究,确定优化的喷涂工艺参数,讨论分析涂层的沉积行为机理。方法采用前驱体溶液等离子喷涂(SPPS)的方法制备纳米Yb_2O_3稳定的ZrO_2(YbSZ)涂层。在传统等离子喷涂的基础上,增加液料雾化装置,雾化喷嘴将溶液雾化后直接注入到等离子弧中,通过控制喷涂距离及喷涂功率,研究了涂层相结构、结晶度、晶粒尺寸以及显微形貌的变化趋势,并且结合显微形貌讨论了沉积机理。结果涂层呈现团聚大颗粒、纳米级粒子、大小均匀的孔隙三种显微形貌,大颗粒之间呈堆积形态。当喷涂功率为30 kW时,涂层呈现m-ZrO_2,平均晶粒尺寸达669 nm。随着喷涂距离、喷涂功率的增加,样品中检测到单一的t-ZrO_2相,而且纳米尺寸颗粒的数量大大增加,孔径变小。随着喷涂距离由60 mm增加到100 mm,平均晶粒尺寸先由429 nm减小到177 nm,随后又增加到319 nm。结论喷涂参数影响晶粒的结晶度、晶粒尺寸以及涂层的显微形貌,低功率下得到的涂层存在糊状未结晶组织。增大喷涂功率,可以有效增大结晶度和晶粒尺寸;随着喷涂距离的增大,晶粒尺寸先减小后增大。雾化液滴在等离子火焰中一般要经历浓缩、饱和、固化、析晶形核长大、粒子重熔扁平化的历程,喷涂功率越高,经历温区越高,液滴演变就越充分,通过优化工艺参数可以得到不同结构性能的功能涂层。     

Plasma spray deposition of nylon 11 coatings

Nylon 11 coatings up to 2mm in thickness have been successfully deposited by plasma spraying. The work showed that control of the torch traverse speed and arc power were essential for the production of sound coatings. The coating quality deteriorated rapidly for torch traverse speeds below 100mms^?1 due to thermal degradation, under the conditions used. An optimum in arc power for maximum wear resistance and minimum porosity was found to exist: power levels below 21kW gave incomplete melting whereas those above caused thermal degradation. The presence of voids in the coatings had a major influence on properties and their formation is attributed to entrapped gas in the interstices between unmelted particles, gas evolution during degradation and porosity in the feed powder. The porosity and wear peformance of the coatings were controllable by the plama spraying parameters. Adhesive transfer was a principal wear mechanism under sliding contact with fracture occurring along the splat boundaries.     

CO2气氛和喷涂距离对电弧喷涂铁基非晶涂层组织及耐蚀性能的影响

为提高电弧喷涂铁基非晶涂层的非晶含量及耐蚀性,以CO₂为载流气体代替空气进行电弧喷涂试验,并研究喷涂距离对涂层组织与耐蚀性的影响。结果表明,喷涂层的厚度约为200 μm,涂层均主要由结晶相与非晶相构成。相比于空气介质,CO₂抑制了晶化,从而提高了涂层中的非晶含量。同时,喷涂距离对涂层的组织及耐蚀性能有较大影响。随着喷涂距离的增加,涂层中的非晶含量减少。当喷涂距离为100 mm时,涂层具有最高的开路电位-0.498 V(vs SCE)及最小的自腐蚀电流密度4.281 μA/cm²,耐蚀性能最好;当喷涂距离为150 mm时,涂层的耐蚀性最差。提高非晶含量和组织的均匀性可增强该涂层的耐蚀性能。     

Effect of flame conditions on abrasive wear performance of HVOF sprayed nanostructured WC-12Co coatings

Nanostructured WC-12Co coatings were deposited by high velocity oxy-fuel (HVOF) spraying with an agglomerated powder. The effect of flame conditions on the microstructure of the nanostructured coatings was investigated. The wear properties of the coatings were characterized using a dry rubber-wheel wear test. The results show that the nanostructured WC-Co coatings consist of WC, W2C, W and an amorphous binder phase. The microstructure of the coating is significantly influenced by the ratio of oxygen flow to fuel flow. Under the lower ratio of oxygen/fuel flow, the nanostructured coating presents a relative dense microstructure and severe decarburization of WC phase occurs during spraying. With increasing ratio of oxygen/fuel flow, the bonding of WC particles in the coating becomes loose resulting from the original structure of feedstock and the decarburization of WC becomes less owing to limited heating to the powder. Both the decarburization of WC particles in spraying and the bonding among WC particles in the coatings affect the wear performance. The examination of the worn surfaces of the nanostructured coatings reveals that the dominant wear mechanisms would be spalling from the interface of WCCo splats when spray particles undergo a limited melting. While the melting state of the spray particles is improved,the dominant wear mechanisms become the plastic deformation and plowing of the matrix and spalling of WC particles from the matrix.     

新型大气长层流等离子体喷涂方法和研究进展

介绍了一种新型大气等离子喷涂方法,该方法采用特殊内通道结构的直流非转移电弧等离子发生器,可以直接在大气条件下获得长度100～1000 mm之间变化的等离子射流。在大气条件下,等离子射流的流动特性具有"长、直、准"的层流或类层流状态,工作时噪音小于80 dB。在工作参数范围内,等离子射流的长度在固定总气流量条件下可以随输出功率的增加而增长;射流的长度在固定输出功率的条件下随总气流量的增加而减小。当使用在大气等离子喷涂技术中时,会为飞行粉末颗粒带来超长的加热和加速过程。文中详细介绍了大气层流等离子喷涂技术的研究历史和研究现状,以及研究团队利用该新型技术制备的6种涂层的显微结构、颗粒的飞行和加热特点,并对比了目前其他大气等离子喷涂技术的结果。结果表明,文中介绍的方法在最低的输出功率和气流量条件下,为金属和陶瓷颗粒提供了超长的飞行和加热条件,表现为较低的颗粒飞行速度和超高的颗粒表面温度。可以在不同的射流长度或喷涂距离下,获得不同的颗粒熔化状态或涂层结构,并发现可以直接在大气条件下获得大规模气液共沉积的涂层。     

电弧喷涂制备铁基耐磨陶瓷涂层的工艺优化

采用电弧喷涂方法在Q235钢基体上喷涂铁基涂层,并用正交设计的方法对工艺参数进行了优化。确定优化后的工艺参数为:喷涂电流180A,喷涂电压32V,雾化空气压力0.6MPa,喷涂距离100mm。试验结果表明:采用优化后的最优工艺参数进行喷涂,所得涂层的耐磨性为Q235钢的13.7倍。     

Configuration optimization of high velocity arc spraying gun

In order to improve the in-flight characteristics of the atomizing droplets during high velocity wire arc spraying (HVAS), some changes have been operated on the original design of the HVAS gun configuration. A comparative study was carried out to investigate the microstructure and properties of the coatings produced by the original design spraying gun and the modified one, using 3Cr13 wires of 3 mm in diameter. The characteristics of their jets were examined during spraying. The results indicate that, the included angle between the two wires and the distance from the nozzle to the meeting point of the two vires may have a strong influence on the characteristics of the in-flight droplets and then the coatings. The jet divergence is found to be lower than that of the original one (about 12° against 25°). By modified gun, the adhesion strength, the microhardness and porosity of the coating deposited by modified gun are increased by 39% and 9% respectively. And the porosity of the coatings is decreased by 57%.