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1、Introduction to Powder Coating粉末涂料介绍,Metal Pretreatment for use withPowder Coatings金属前处理,Metal Preparation金属的处理,Pretreatment is a process intended to prevent the corrosion of the painted metal.前处理是一种提高耐腐蚀的工艺,Fe2 + O2 + H2O=RUST,Iron reacts with oxygen and water in the atmosphere creating a powdery b
2、rown mess, not very ornamental, and continuous until no solid metal remains.铁在空气中会与氧气和水反应生成褐色的物质,Metal Preparation金属处理,Several methods of corrosion prevention can be used几种防腐蚀的方法For Steel:铁：Automotive applications 汽车业 Primer : Underseals : Layers of Paint.,Several methods of corrosion prevention can
3、 be used几种防腐蚀的方法For Steel:铁：Architectural Applications 建筑业Galvanising : Anti Corrosive Primer* Galvanising covering with a layer of zinc.,Metal Preparation金属处理,Metal Preparation金属处理,Metal Preparation金属处理,Several methods of corrosion prevention can be used几种防腐蚀的方法For Aluminium:铝：Aluminium oxidises to
4、 form a white corrosion product铝被氧化后形成白色的物质Architectural Applications 建筑业 Anodise : Acid Primers,Metal Preparation金属处理,Why Pretreatment ?为什么要前处理？,Powder coatings are used to enhance the appearance of buildings, machines, furniture,appliances:粉末涂料用于改善建筑，机械设备，家具，以及其它器具的表面：Designers and architects are
5、searching to give distinction in terms of colour and effects.设计师和建筑师提供了包括颜色和效果在内的标准等级The problem is that all paints are porous：所有的涂料均不同程度的存在会渗水的小孔,Metal Preparation金属处理,Molecules of water and salt can penetrate through the paint film.When they reach the metal surface the effect is worse than if the
6、metal is uncoated.The answer = Pretreatment水和盐分子可以渗透漆膜，一旦它们与金属表面接触，产生的影响甚至比没有喷涂还要糟糕。要解决这个问题就需要前处理。,Metal Preparation金属处理,Pretreatment:前处理The chemical conversion of the metal surface before applying the powder coating.The metal then resists corrosion and the conversion permanently improves the adhesi
7、on of the coating.在使用粉末涂料以前用化学方法对金属表面进行处理，可以改善耐腐蚀性和增加涂层的附着力。,Metal Preparation金属处理,The performance of the powder coating is only going to be as good as the metal preparation. We will cover three types of metal treatment systems粉末涂料的功能类似于金属处理，我们将介绍三种的金属处理方法 Iron Phosphate for Steel用于铁系的磷酸铁 Zinc Phosp
8、hate for Steel用于铁系的磷酸锌 Chromate for Aluminium用于铝的铬酸盐Other systems can be used and information is available.当然还有其它处理方法,Metal Preparation Iron Phosphate金属处理 磷酸铁,Metal pretreatment can be applied by spray or dipping.金属前处理可以借助喷淋或浸渍,In the case of iron phosphate the process could look like this:下面是磷酸铁的工艺
9、流程,Stages 1, 2 and 3 can be either spray or dip步骤1，2和3均可采用喷淋或浸渍,DRAIN,DRAIN,Stage 1Clean&Phosphate,Stage 2Rinse,Stage 3Rinse&Seal,WorkFlow,Metal Preparation Iron Phosphate金属处理 磷酸铁,Typical 3 Stage System典型的3步骤流程Metal SubstrateSteel Phosphatising System金属基材None Ferrous Clean and EtchStage time duratio
10、n1 90 seconds不同步骤所需的时间2 45 seconds3 30 secondsStage temperature 1，2和3步骤所需的温度40 60oCDrying/干燥温度100 120oCTypical concentration 2 3 % by volume典型的浓度Typical acidity典型的酸值pH 3.5 5.5Typical coating weight典型的膜重20 40 mg/ft.,Metal Preparation Zinc Phosphate金属处理 磷酸锌,Zinc Phosphate process for steel tends to be
11、 more complicated磷酸锌的工艺流程复杂一些,Stage 1Clean,Stage 2Rinse,Stage 3Phos-phate,Stage 4Rinse,Stage 5Rinse,DRAIN,DRAIN,DRAIN,DRAIN,Metal Preparation金属处理,Dwell Time :Each stage depends on:各阶段所需的时间，受下面的因素控制 The amount of pretreatment chemical dissolved in water溶于水的前处理化学药品的浓度 The age of the chemical化学药品的有效时间R
12、egular checking is required to give consistent good results at least twice per shift.通常要经常检查前处理的状态一个班至少两次,Metal Preparation Zinc Phosphate金属处理 磷酸锌,Typical 5 Stage System典型5步骤流程Metal SubstrateSteel Phosphatising System金属基材None Ferrous Clean and EtchStage time duration1 90 seconds不同步骤所需的时间2 45 seconds
13、3 60 seconds4 30 seconds5 30 secondsStage temperature温度40 60oCDrying干燥温度100 120oCTypical concentration典型浓度2 4 % by volumeTypical acidity1 = alkaline酸碱性2 = acidicTypical coating weight40 70 mg/ft.典型的膜重,Metal Pretreatment - BS 3189 Type 3,Spray Phosphate Plant,9 stage pretreatment九步法 Degrease脱脂 Rinse水
14、洗 Rinse水洗 Rinse水洗Acid Etch (phosphoric acid)表调Zinc Phosphate磷酸锌磷化 Rinse水洗 Rinse水洗 De-ionised water去离子水水洗 Dry 干燥Quality Standard BS6497参考英国标准BS6497,Metal Pretreatment Quality Control金属前处理 质量控制,Titration Checks:检测项目：1. Cleaner2. Rinses3. Acid Concentration4. Rinse5. Phosphate Concentration and coating
15、 weight7. Rinse8. ObservationsChecked at regular intervals during normal production and before production commences以上项目应在生产过程中定时和生产前进行检验,Metal PretreatmentDry金属前处理干燥,To ensure metal surface is dry ready for powder coating.在喷涂粉末涂料前必须保证金属工件已经完全干燥,Drying oven -Phosphate Plant,Metal Preparation Chromate
16、金属处理鉻酸盐,For aluminium chromate conversion铝铬酸盐处理,British Standards exist for the conversion of aluminium BS 6496适用于铝的英国标准BS6496The same conversion can be used for Galvanised steel-BS 6497适用于电镀铁的英国标准BS6497,Stage 1Clean,Stage 2Rinse,Stage 3Etch,Stage 4Rinse,Stage 5Chrom-ate,Stage6 7Rinse,Stage 8DeminRi
17、nse,DRAIN,DRAIN,DRAIN,DRAIN,DRAIN,DRAIN,Metal Preparation Chromate金属处理鉻酸盐,Typical 7 Stage System七步法Metal SubstrateAluminium / Aluminium Alloys金属基材Galvanised Steel Clean and EtchStage 1CleaningStage 2RinseStage 3Deoxidise metal surfaceStage 4RinseStage 5ChromateStage 6RinseStage 7Acidulated RinseStag
18、e Temperature80 100oCDrying90 95oCDo not overheat at the dry off stage干燥温度不能过高,Metal Preparation Chromate金属处理鉻酸盐,Chromate conversion to Aluminium and Galvanised steel鉻酸盐处理完铝和电镀铁后的变化,Yellow Chromate ConversionTypical Coating黄色鉻酸盐的变化Weight (g/m2)Pale Yellow0.2 0.7Gold0.7 1.6Brown1.6 3.5Green mix chrom
19、ate/phosphate0.5 2.0,For Powder Coating a lightweight coating is recommended In the range 0.2 2.0 g/m2 应用于粉末涂料，膜重一般在0.22.0g/m2,Spraying and ApplicationofPowder Coatings粉末涂料的喷涂与应用,Powder Application Systems粉末涂料的应用系统,Powder Application SystemsFeed Systems粉末涂料应用系统供粉系统,Direct feed system from Drum to Gu
20、n.粉末涂料直接从粉桶送至喷枪The system shown feeds 1 gun右图是只供一个喷枪的直接供粉系统,Powder Application SystemsFeed Systems粉末涂料应用系统供粉系统,Direct feed system directly from a 25 kilo box.This system is set up to feed 2 guns.Used mainly in manual operations.右图为直接从粉末涂料的包装箱至喷枪的供粉系统。图中的设备适用于两把喷枪，通常用于人工喷涂。,Powder Application Systems
21、Feed Systems粉末涂料应用系统供粉系统,Bulk feed system, powder is supplied in a fibre bag. Weight of powder up to 1,000 kilos per bag.Used mainly on automatic plants where colour change is limited.大型供粉系统，粉末涂料一般1吨一个包装，用于自动喷涂系统，限于换色较少的场合。,Powder Fluidisation Systems粉末涂料流化系统,Dry air passes through a membrane giving
22、 the powder liquid qualities.干燥的空气通过微孔板，使粉末涂料象水一样流动。,The air must be dry and free from water and oil.空气必须除水和油,Powder Delivery Systems粉末涂料的传送系统,Powder Delivery Systems粉末涂料的传送系统,Actual powder feed systemVenturi feed from fluid bed.右图是用文氏管从流化床吸取粉末的送粉系统,Forces at work on the Powder Particles,At any one
23、time 4 forces are at work on the powder particle as it travels from the gun to the earthed work-piece.粉末在离开喷枪到达工件时受4种力的影响Air Resistance Electrostatic AttractionWeight (Gravity) Aerodynamic Force,Powder Charging Systems,There are 2 major categories in charging of powder coating corona and tribo:粉末涂料主
24、要有两种带电方法静电/摩擦,Gun TypeCharge Location充电位置InternalExternalRemotePowder SupplyXXCorona静电法Integrated GunPowder SupplyXXTribo摩擦带电法X,Corona Charging Systems静电带电系统,In this method, a high voltage generator is used to charge an electrode at the tip which creates an electrostatic field (or corona) between th
25、e gun and the work-piece.利用高压电极使粉末带电，并在喷枪与工件间形成电场,External Charging System/外充电系统,Corona Charging Systems静电带电系统,Corona charging- manual system/手动枪- automatic system/自动枪,Corona Charging Systems静电带电系统,Internal Charging System内充电系统,Corona Nozzle Systems静电枪的喷嘴,The type of product toBe coated will influen
26、ce The nozzle to be used on theSpray gun, two types are shown,Corona Nozzle Systems静电枪的喷嘴,Conical Spray Nozzles used to give an evenly distributed film thickness over flat panels.圆锥型的喷嘴一般用于喷涂平面，并得到膜厚均匀的涂层。Interpon AF particle managed powder being applied on domestic appliances.右图为Interpon AF粉末涂料用于家用
27、设备,Corona Charging Systems静电带电法,The high voltage power supply charges the electrode高压发生器使喷枪电极带电 The concentrated charge creates an electrostatic field带上电荷后形成静电场 The electrostatic field causes the air to ionize and generate a corona静电场使空气电离形成电晕 The corona emits electrons电晕放射出电子 The electrons are pick
28、ed up by oxygen molecules forming negative ions这些电子借助氧分子形成负离子,Corona Charging Systems cont.静电带电法,The ions follow the field lines负离子沿着电力线移动 The powder particles distort the field around them粉末涂料粒子使周围的电力线产生扭曲 The distorted field lines direct ions to the powder particles扭曲后的电力线引导离子被粉末涂料粒子吸附 The ions bo
29、mbard the powder particles and transfer the electrons giving the particles a negative charge吸附的离子轰击粉末粒子，并使其带上负电，形成负极,Tribo Charging Systems摩擦带电法,Tribo electricity is generated by the friction of one material on another.In Tribo charged spray guns, the powder rubs on a specially formulated and shaped
30、 surface which allows charge to transfer.摩擦带电是通过不同物质摩擦形成的，摩擦枪可以使粉末与特殊设计并有特殊结构的表面摩擦而带电,Tribo Charging Systems摩擦带电法,Tribo Charging Systems摩擦带电法,Tribo nozzles in different configurations.不同结构的摩擦枪喷嘴,Electrostatic Fluid Bed Systems静电流化床法,Powder Penetration粉末的吸附,The picture shows the development of the co
31、rona (red dotted area).Articles passing through are charged with the negative ions (-).The charged powder particles are attracted to the earthed substrate.右图显示了电场，电力线，粉末的充电及被接地的工件吸附过程。,Powder Penetration粉末的穿透,Achieving penetration into deep recesses in most important when applying powder coating.粉末涂
32、料能否到达死角这对粉末涂料的应用来说很重要,The most effective controls are the nozzle patternAnd air assistance.有效的控制方法是选择合适外形的喷嘴及调整辅助空气,It is possible to overcome the “Faraday Cage Effect”现在，克服“法拉第”效应已成为一种可能,Powder Penetration粉末的穿透,Reducing the “Faraday Cage” Effect减弱“法拉第”效应,To reduce the effect it is necessaryTo assis
33、t in the creation of charged airParticles inside the recess. This should be彻achieved by increasing the air stream.可以借助加大传送空气的压力来减弱“法拉第”效应,Faraday Cage Effect“法拉第”效应,A Faraday cage can technically be defined as an area within which there is no electrostatic field.In finishing, this term is applied mo
34、re loosely, and generally refers to an area such as inside corners or cavities that are difficult to coat.The reason why these areas are difficult to coat is that the adjacent surfaces to the inside of the corner attract the electrostatic filed, therefore deflecting the powder from penetrating into
35、the recessed areas.At the same time , this recessed area is difficult for the aerodynamic forces to penetrate into without blowing powder off already coated areas.法拉第区域可以被认为是静电屏蔽区。实际应用中定义更宽松，通常是指死角和洞等难喷涂区域。难喷涂的原因是这些区域的外围吸引了电荷，这样粉末就不能被吸附。 另外，从空气动力学来将，输送空气将粉末吹至这些区域也很难。,Back Ionisation反弹效应,A = powder a
36、ttracted to the earthed componentB = build up to correct film thicknessC = ionised air within the powder film repels oncoming particles A = 粉末吸附在接地工件B = 形成合适的膜厚C = 在涂层上的离子云抵制吸附带有同类电荷的粉末,Powder Recovery Integrated System粉末回收系统,Integrated Spray / Recovery Booth System完整的喷涂/回收系统,Powder Recovery Systems
37、粉末回收系统,Typical cartridge back-Pulse cleaning design.Used in cartridge Recovery systems.典型脉冲自清理设计，通常适用于桶状回收系统,Powder Recovery Systems粉末回收系统,Cyclone Recovery System,The cyclone is used to separate the powder particles from the air.The air is driven round the sides of the cyclone, reducing in velocity
38、and releasing the powder to be collected at the base.Fine powder is usually transported out of the cyclone on the air flow.旋风分离器根据粒径分离粉末，空气沿着旋风分离器壁做圆周运动，速度渐渐降低，并释放被收集的粉末至底部。细粉通常会随流动空气离开旋风分离器。,Powder Recovery Systems粉末回收系统,Fine powder is collected on a filter system in the “after filters”. The pneuma
39、tic air pulse ensures air flow is consistent and the fine powder collected for disposal.细粉通过滤芯滤层被收集。有力的气体脉冲保证了空气流动的连续性及需被分离的细粉收集。,Powder Recovery Systems粉末回收系统,A motor generates the air flow. Ensuring the correct air volume and velocity is maintained.电机提供流动空气，并保证气体流量和速度。,Powder in-line Sieving Syste
40、ms粉末过筛系统,Rotary In-Line Sieve旋转筛,Powder Vibrating Sieving Systems震动筛,Vibrating sievesare designed towork either:- Free standing- In-line震动筛适用于：- 独立区域- 流水线,Powder Reciprocator Cycle粉末喷涂的往复机构,Cycle Rate往复速度,=,No. Of Guns x Pitch of Guns x 60喷枪数量x喷枪位置x60,Conveyor Speed (mm/min)传送链速度（毫米/分钟）,This will en
41、sure striations do not occur on the components being coated.在喷涂中要保证不要形成带状涂层。,Application Practical实际应用,Stoving and CuringofPowder Coatings固化炉及粉末涂料的固化,Types of Oven固化炉的类型,Convection energy is transmitted by air circulation to heat the components对流 热量通过空气流动传送，加热工件 Radiation energy is transmitted direc
42、tly onto the parts without heating air between the parts and the radiation source辐射 热量直接从辐射源被传送至工件而无需空气作媒体 Induction energy is transmitted through inducing electrical eddy currents that generate heat in the metal parts 感应 热量借助电流来传送来加热金属工件,The Baking Process固化过程,The baking stage, during which the pow
43、der coating melts, flows, gels and finally chemically reacts (cross-linking) and cures. It is critical to the performance of the coating that the temperature and time at temperature are maintained.Most baking ovens are designed to take the substrate through a pre-programmed time temperature profile.
44、固化过程包括粉末的熔融，流平，凝胶最后发生化学反应形成涂层。固化温度极其所占时间是非常重要的，大多数固化炉借助预先设置固化时间（温度曲线）来设计。,Powder Application Radiation Stoving粉末的辐射固化,Gas fires Infra-Red oven usedfor industrial components.左图为用于固化工业用品的瓦斯红外炉,I-R emitters inside the oven cure the powder film when in direct line, as radiation energy.右图为通过炉内红外发生器（热源）固化
45、粉末涂料,I-R is often used to boost the curing in front of a conventional air circulating oven.红外热常常被用于传统的利用空气循环的固化炉的前段,Powder Application Induction Stoving粉末的感应固化,Pipes passing through an induction coil at between 12 - 15 ft/min. 管子通过感应圈（速度为12-15英尺/分钟）,Induction is extremely effective when curing powde
46、r coating applied to wire.感应固化非常适和用于金属线的粉末涂料的固化,Stoving Effects固化程度,Problem Solving问题的解决,Top 5 Problems with Application使用中的五个主要问题,Differences in gloss between standard and coated parts- Understoved High gloss- Overstoved Low in gloss。 在标准与喷涂的工件之间光泽不一样- 固化不完全 光泽高- 过度固化 光泽低Differences in colour betwe
47、en parts- Film thickness differences- Us of 2 different products (from 2 suppliers)喷涂的工件之间的颜色不同- 膜厚不同- 使用不同的涂料（从两个供应商）,Top 5 Problems with Application使用中的五个主要问题,Poor Adhesion Chipping- Understoved- Poor cleaning or pretreatment附着力不好 碎片剥落- 固化不完全- 工件清理或前处理不好Poor attraction to work piece- Bad earth- Gu
48、n HT not adjusted- Voltage not switched on吸附不良- 接地不好- 喷枪设置不好,Top 5 Problems with Application使用中的五个主要问题,Contamination in coating Bits- Poor booth/gun cleaning- Contamination from plant oil and grease from conveyor- Poor metal cleaning。 污染 砂粒- 喷房和喷枪清理不好- 车间的污染 传送链上的油脂- 工件清理不好,Top Problems after application使用后的主要问题,Corrosion on parts cutAfter powder coating工件在喷涂粉末涂料后在切口处腐蚀,Top Problems after application使用后的主要问题,Dirt RetentionPoor maintenance耐污性差维持性能不好,Top Problems after application使用后的主要问题,Water-spot blistering水泡Poor pre-treatment前处理不佳,
