1、铁基粉末冶金材料铁基粉末冶金材料内内 容容 提提 要要n概述概述n工艺过程工艺过程n产品种类产品种类n混料、成型、烧结及后处理混料、成型、烧结及后处理n发展趋势发展趋势粉末冶金简介粉末冶金简介粉末冶金是：通过对所需基础粉末，合金粉末及添加剂混合，然后将混粉填充在具有要求形状的模腔内进行压制成形，再将成型坯体在保护气氛下进行烧结使各种颗粒形成冶金结合，经过后续处理后得到最终产品。由于精确的成型技术，粉末冶金产品具有以下特点：近净成型 形状复杂 优良的尺寸精度.粉粉 末末 冶冶 金金 简简 介介粉末冶金技术发展迅速：其原料涵盖了近乎所有技术元素 产品形状复杂程度日益提高粉末冶金产业主要分为两个领域
2、：铁基粉末冶金 非铁基粉末冶金铁基粉末冶金材料铁基粉末冶金材料n自润滑制品自润滑制品n结构件结构件n软磁材料软磁材料自自 润润 滑滑 零零 件件 结结 构构 件件 零零 件件 软软 磁磁 零零 件件粉粉 末末 冶冶 金金 产产 品品 优优 势势n近净成型近净成型n期望的力学性能期望的力学性能n大规模的生产和重复性好大规模的生产和重复性好n表面光洁度表面光洁度 n高尺寸精度高尺寸精度 n允许不同材料组合允许不同材料组合n多孔及孔隙度可控（自润滑材料）多孔及孔隙度可控（自润滑材料）n良好的磁性能（软磁材料）良好的磁性能（软磁材料）粉末冶金基本工艺过程粉末冶金基本工艺过程后后 续续 处处 理理粉粉
3、末末 原原 料料n基粉类型基粉类型n合金体系合金体系n合金化方式合金化方式基 粉 的 选 择混混 料料n混料要求混料要求n混合方式混合方式n均匀性与偏析均匀性与偏析n松装密度与流动性松装密度与流动性混粉及装粉过程中产生的细粉团聚混粉及装粉过程中产生的细粉团聚压压 制制n压制方式压制方式n生坯密度与密度均匀性生坯密度与密度均匀性n生坯强度生坯强度 n生坯缺陷生坯缺陷充模过程充模过程n Care must be taken when filling thin sections as bridges may occur.The min.cross section size is about 1mm.
4、装粉高度与模冲进入量的计算装粉高度与模冲进入量的计算DieCRUPLOPLIPt1t2H2LOPLIPUPDieH1FD=3.2g/cm3GD=7.2g/cm3Example:t1=10mmt2=25mmH1=22.5mmH2=56 mmUPentry=31mmH1=GD/FD*t1H2=GD/FD*t2UPentry=H2-t2粉末压制粉末压制摩擦力摩擦力nBetween powder particlesnBetween punches and the die-wallnBetween punches and powder particlesnBetween powder particles
5、 and the die-wall摩擦力导致的后果摩擦力导致的后果nLosses of the applied forcenVariation of pressure and green densitynHigher ejection forcesn(Wear of the tool-set)密度分布密度分布双向压制示意图双向压制示意图a)Stationary die,two moving punches.b)Stationary lower punch and floating die.c)Stationary lower punch,and the die being withdrawn
6、at half the speed of the top punch.如何减小摩擦力如何减小摩擦力n加入润滑剂加入润滑剂n模壁润滑模壁润滑n优化压制工艺优化压制工艺-压制速度压制速度-压制温度压制温度-滑动距离滑动距离-润滑剂含量对生坯理论密度的影响润滑剂含量对生坯理论密度的影响 ASC100.29 Amount of lubricant不同润滑剂对生坯理论密度的影响不同润滑剂对生坯理论密度的影响 ASC100.29 脱模力的变化过程脱模力的变化过程n Due to residual radial stresses a significant force is required to ejec
7、t compacts from the die.RRSs should be kept to a minimum to avoid high ejection forces,hence avoid tooling problems.模具润滑状况对脱模力的影响模具润滑状况对脱模力的影响Good lubrication模具润滑状况对脱模力的影响模具润滑状况对脱模力的影响n Excessive die wall wear or insufficient lubrication may result in cold welding of the compact to the die wall.Good
8、 lubricationBad lubrication Results in increased ejection force and stick-slip behaviour(squeaky noise)压制缺陷压制缺陷SEM image of a crack no sintering necks过过 压压 分分 层层烧烧 结结n烧结的作用烧结的作用 脱除润滑剂脱除润滑剂 冶金粘结冶金粘结 元素扩散元素扩散 尺寸变化尺寸变化 微观结构微观结构 防止氧化与还原氧化物防止氧化与还原氧化物n烧结温度、烧结时间、烧结气氛烧结温度、烧结时间、烧结气氛烧结过程烧结过程Metal powder compa
9、ct Porous metal Sintered state(bonding between particles)Green state(cold welding)生坯与烧结件生坯与烧结件After compactionAfter sintering烧结工艺示意图烧结工艺示意图Temp.TimeRT Delubrication(300-700C)C-dissolution(800-950C)4321 Sintering(1100-1300C)Cooling (Cooling Rate)1234影响烧结的因素影响烧结的因素nTemperaturenTimenAtmospherenMaterial
10、 composition nAlloying methodnLubricant contentnSintering cycle烧结过程的实质烧结过程的实质 Particle bonding Microstructure Dimensional changeSintering necksPoresPhases/structuresSizeShapeAlloyingHomogenization烧结驱动力烧结驱动力V1+V2=V3E1 +E2 E3123E1 +E2E3EHigh energy stateLow energy stateDriving Force:Surface energy固态烧结
11、固态烧结 By the Diffusion of the metal atomsCu spheres孔隙变化孔隙变化From sharp corners to flatter parts of the pore surfaceFrom small pores to near-by larger pores and grain boundaries均匀化过程均匀化过程 Ni in Fe-base影响均匀化的因素影响均匀化的因素Ni particle size:5 um,10 umTemperature:1000-1300CWeighing factor:Temperature Ni partic
12、le size TimeTime:0.5-500 h烧结的分类烧结的分类nTemperature(1150C)nFurnace(batch,pusher,belt,walking beam)nAtmosphere(“vacuum”,Endo,N2/H2)nState(liquid,solid)nPressure(atmospheric,pressure-assisted)高温烧结高温烧结nAccelerates the atomic motion(better sintering necks)nImproves the surface reduction of particles(activa
13、tes sintering)nIncreases the sintered densitynImproves the homogenizationnImproves pore roundingnImproves mechanical properties 瞬时液相烧结瞬时液相烧结Secondary poreFe Cu系膨胀机理系膨胀机理90%Fe10%Cu1150 CFe-Cu 系与系与Fe-Cu-C 系的尺寸变化系的尺寸变化 CuCu+1%C烧结常见的问题烧结常见的问题nAchieve sufficiently tight tolerancesnOxidation(alloying elem
14、ents,sintering atmosphere)nCarburisation(temperature,sintering atmosphere)nDecarburisation(temperature,sintering atmosphere)nPoor surface finish(delubrification)影响尺寸变化的因素影响尺寸变化的因素nParticle sizenAlloying elementnUneven filling and compaction nUneven distribution of alloying elements in the componentn
15、Liquid phase formationnSintering temperature and timenUneven temperature distribution of the sintering furnacenPoor control of gas flow in the sintering furnace脱蜡缺陷脱蜡缺陷(Blistering)Fe+2.5%Ni+0.4%C烧结缺陷烧结缺陷 Poor sintering necks(sponge)Poor sintering necks(atomised)Oxidation during sintering弱烧结颈和游离石墨弱烧结
16、颈和游离石墨烧结脱碳烧结脱碳 NC100.24+Cu+Ni+1%C D.AB+0.6%C Astaloy CrM+0.3%C烧结渗碳烧结渗碳 PASC 30+0%C D.HP-1+0.5%C 过低的烧结温度过低的烧结温度 Free Cu in Distaloy material后后 续续 处处 理理TreatmentDefinitionExamplesCoatings-a deposition of a layer of a separate material onto the surface of the substrate without any chemical reactionElec
17、troplatingPaintingmetallizingChemical conversion treatmentsA chemical reaction between the surface layers of the original substrate and an external reactantSteam treatmentPhosphatising,etcThermochemical treatmentsDiffusion of other species,such as C,N,into the surface layers of the original substrat
18、eCarburisingCarbonitridingNitrocarburisingNitridingPlasma treatments,etc后后 续续 处处 理理TreatmentDefinitionExamplesThermal treatmentsChange in microstructure of the surface layers of the original substrate by thermally cycling through a phase transformationInduction hardeningLaser hardeningMechanical def
19、ormationMechanical deformation in the surface layers of the original substrate,mainly to induce compressive stresses,but also to provide densification of the surface layerSurface cold rolling,etc发发 展展 趋趋 势势n高密度高密度n高性能高性能n高尺寸精度高尺寸精度n低单位成本低单位成本n新工艺新工艺n新材料新材料发发 展展 趋趋 势势HighMediumLow Very lowVery poor P
20、oor Medium Good Very goodPlasticsCasting+ForgingPMTolerancesStrength粉 末 冶 金 关 注 领 域高高 中中低低 中中 高高低低Fe-Cr-Mo-Ni-CLiquid phaseFe-Cr-Mo-Ni-CMixAstaloy CrMD.HP-1Fe-Cu-Mo-Ni-CFe-Cu-Mo-Ni-CStarmixDistaloy AEAstaloy CrLFe-Cu-CCu met.Fe-Cu-CDistaloy ACuFe-Cu-CDist.ACu,Starmix 尺寸公差尺寸公差强强 度度 粉末冶金发展趋势粉末冶金发展趋势.（.）成立于2004年，专注于企业管理培训。提供60万企业管理资料下载，详情查看：http:/
