Warm compaction powder metallurgy of Cu

A series of experiments were carried out using different admixed lubricant contents, different compaction pressures and temperatures in order to study the warm compaction of copper powder. Results show that too much admixed lubricant will lead to the squeeze out of the lubricant from the compact during the warm compaction processing of Cu powder. Results also show that blisters can be found in sintered samples that contain lubricant less than 0.15%(mass fraction). Optimal warm compaction parameters for producing high density powder metallurgy copper material are obtained. Compacts with green density of 8.6 g/cm^3 and a sintered density of 8.83 g/cm3 can be produced by warm compacting the Cu powder, which contains 0.2% admixed lubricant, and is compacted at 145℃ with a pressure of 700 MPa.     

Die wall lubricated warm compaction of iron-based powder metallurgy material

Lubricant is harmful to the mechanical properties of the sintered materials,Die wall lubrication was applied on warm compaction powder metallurgy in the hope of reducing the concentration level of the admixed lubricant.Iron-based samples were prepared by die wall lubricated warm compaction at 175℃,using a compacting pressure of 550MPa.Emulsified polytetrafluoroethylene(PTFE) was used as die wall lubricant.Admixed lubricant concentration ranging from 0 to 0.5% was tested.Extremely low admixed lubricant contents were used.Results show that in addition to the decrease in ejection forces,the green density of the compacts increases with the decrease of admixed lubricant content until it reaches the maximum at 0.06% of lubrcant content,then decreases with the decrease of admixed lubricant content.The mechanical properties of the sintered compacts that contain more than 0.06% admixed lubricant are better than those of the samples that contain lesser lubricant.No scoring was observed in all die wall lubricated experiments.     

Warm compaction of Al2O3 particulate reinforced powder metallurgy iron-base composite

1　ＩＮＴＲＯＤＵＣＴＩＯＮＲｅｆｅｒｅｎｃｅｓｆｏｃｕｓｅｄｏｎｗａｒｍｃｏｍｐａｃｔｉｏｎｗｅｒｅｆｉｒｓｔｐｕｂｌｉｓｈｅｄｉｎ 1994 [1,2 ] .Ｉｔｉｓａｒｅｌａｔｉｖｅｌｙｓｉｍｐｌｅａｎｄｅｃｏｎｏｍｉｃａｌｐｒｏｃｅｓｓｔｈａｔｃａｎｐｒｏｄｕｃ     

Coupled mechanical and thermal simulation of warm compaction

1 Introduction Powder metallurgy is an advanced manufactural technology widely used for volume-producing mechanical parts with high performance and high precision[1?3]. Warm compaction is a low cost and effective technique to produce green compact with de…     

Sinter-hardening properties of partially-diffuse alloyed Fe-Cu-Ni-Mo-C material prepared by die wall lubricated warm compaction

The sinter-hardening properties of a partially-diffuse alloyed Fe-2Cu-2Ni- 1Mo- 1C material were investigated. Samples were formed by die wall lubricated warm compaction method, then, sintered in hydrogen atmosphere at 1 150 ℃ for 1 h and cooled at 4.6, 2.9 and 1.5 ℃/s, respectively, from 900 ℃ down to 600℃. Effects of cooling rate on mechanical properties and microstructure of the material were discussed. The results show that when the cooling rate increases, the tensile strength of the material increases, while, the elongation shows opposite result. The sintered material has a tensile strength of 872 MPa and an apparent hardness of HB 257 at a cooling rate of 4.6 ℃/s. Slight shrinkage is observed. Heterogeneous microstructures containing martensite, bainite, pearlite and nickel-rich retained austenite are observed in the material. Higher martensite content can be obtained at higher cooling rate, while, at lower cooling rate, pearlite and retained austenite dominated the microstructure.     

Warm compaction behaviors of iron-based powder lubricated by different kinds of graphite

1　INTRODUCTIONConventionalpowdermetallurgy(PM ) process ingcanproduceiron basedPM partswithadensitylessthan 7.1g/cm3(arelativedensityofapproxi mately 90 % ) .Theirmechanicalpropertiesaresub stantiallylessthanthoseoftheirfulldensitycounter part.IncreasingdensityisthebestwaytoincreasetheperformanceofthePM parts .Therearemanyprocessesthatcanproduceiron basedPM partswithhighdensitysuchaspowderforging ,doublepress/doublesinter(DP/DS)andCuinfiltration ,butwarmcompactionisthemosteconomical…     

Numerical simulation in powder compaction of metallurgy component

1Introduction Forming multi-level component in die compaction,the density is more or less inhomogeneous depending onthe part geometry,the tool design and the frictionbetween powder and die wall[1?3].The productdistortions are result of inhomogeneous densi…     

激光诱导表面改性制备铜基非晶-纳米晶粉末冶金摩擦材料

为改善铜基粉末冶金摩擦材料的摩擦磨损性能,研究了激光诱导表面改性制备铜基非晶-纳米晶粉末冶金摩擦材料方法.采用扫描电镜、透射电镜、X射线衍射仪及硬度计等对粉末冶金摩擦材料层微观组织及性能进行了表征,结果表明:由于激光的急速加热和冷却以及以小质点杂质形式分布于α-Cu基体中的Zn,Sn和Pb元素抑制了再结晶的形核及长大,导致铜基非晶一纳米晶粉末冶金摩擦材料的形成.同时激光表面改性处理后,α-Cu相的晶粒尺寸减小了35%,二类应变均方根值增大39%,位错密度增加97%.聚合生长状态的α-Cu产生边缘溶解,大体积α-Cu枝解细小化.摩擦材料表观硬度提高了12.7%,α-Cu相显微硬度提高了14%.耐磨性能提高45%,摩擦系数升高1%.     

铁基粉末冶金摩擦焊接头分析

摩擦焊是一种固相连接方法，以其优质、离效、低耗环保的突出优点得到了广泛的应用。半个世纪的推广应用，证明了摩擦焊在简化结构和工艺、减少加工、提高质量、降低成本等方面具有独特的效果和显著的作用。摩擦焊不仅可焊接钢、铝、铜．还成功地焊接了高温强度级相差很大的异种金属。随着汽车、飞机及电气制造等部门大量采用粉末冶金材料，国外已采用摩擦焊方法成功地焊接了耪末冶金材料，但目前国内尚无这方面的报道。在此，通过优选工艺参数．成功地焊接了铁基粉末冶金材抖。     

钼粉末温压成形过程的数值模拟研究

运用MSC.MARC有限元分析软件,采用热-机耦合方法,对钼粉末温压成形过程进行了有限元数值模拟,获得了粉末体形变、应力场和相对密度分布等相关数据,为改善钼粉温压成形工艺及优化工艺参数提供了理论依据.     

Debinding and sintering of warm compacted and binder-treated complex iron-base part

Regular elemental powders were used in warm flow compaction instead of the expensive micron-sized powders to fabricate cross-shaped parts. Debinding behaviors, sintering properties and shape consistency of the sintered parts were studied. Binder removal was accomplished by heating green compacts at intermediate temperatures with optimal heating rates until the debinding temperature was reached. Results show that by controlling debinding process, complex parts with good shape consistence can be obtained by warm compaction of binder-treated powder. Fine and shiny surface was obtained and no surface defect can be observed for sintered parts debinded at 2 ℃/min, while defect can be observed in sintered parts debinded at 4 ℃/min.     

Effects of temperature on the mechanical properties of Ti6Al4V powder compacts prepared by magnetic pulse compaction

The effects of temperature (0-500°C) on the compressive strength,hardness,average relative density,and microstructure of Ti6Al4V powder green compacts prepared by magnetic pulse compaction were investigated.The results show that with increasing heating temperature,the compressive strength first increases and then decreases with the maximum value of 976.74 MPa at 400°C.The average relative density and hardness constantly increase,and their values reach 96.11% and HRA 69.8 at 500°C,respectively.The increase o...     

Effects of temperature on the mechanical properties of Ti6Al4V powder compacts prepared by magnetic pulse compaction

The effects of temperature (0–500°C) on the compressive strength, hardness, average relative density, and microstructure of Ti6Al4V powder green compacts prepared by magnetic pulse compaction were investigated. The results show that with increasing heating temperature, the compressive strength first increases and then decreases with the maximum value of 976.74 MPa at 400°C. The average relative density and hardness constantly increase, and their values reach 96.11% and HRA 69.8 at 500°C, respectively. The increase of partial welding is found among the junctions of particles inside the compacts; there is no obvious grain growth inside the compacts within the temperature range.     

Effect of sintering parameters on warm compacted iron-based material

1　INTRODUCTIONItiswellknownthatincreasingdensityisthebestwaytoincreasetheperformanceofpowdermet allurgy(P/M ) parts.ConventionalP/Mprocessingcanproduceiron basedpartswithdensitylessthan 7.1g/cm3(arelativedensityof 90 %approximately) .Theirmechanicalpropertiesaresubstantiallylessthanthoseoftheirfulldensitycounterpart .TherearemanymethodsthatcanproduceP/M partswithrela tivelyhighdensitysuchaswarmcompaction ,hightemperaturesintering ,doublepress/doublesinteringandforging .Warmcompactioni…     

粉末冶金温压成形技术的研究现状

粉末冶金温压成形,在得到较高致密度零件的同时,可以较铸造和锻造显著的降低原料成本,缩短零件的研制周期,具有重要的研究价值。本文概述了国内外温压成形技术的应用、发展现状及温压成形工艺的关键技术,指出了粉末冶金温压成形技术的发展方向。     

润滑剂含量不同时W-Ni-Fe合金的温压行为

研究90W-7Ni-3Fe合金的温压成形工艺,探讨润滑剂含量不同时温压行为对硬粉的作用,并比较温压工艺与常温压制工艺的不同。结果表明：在相同单位压制压力下,温压压坯密度明显高于常温压制的;润滑剂含量为0.6%（质量分数）时压坯密度达到最大值,温压压制与常压压制相比,压坯密度增加0.26 g/cm3;润滑剂含量超过0.6%后,压坯密度又逐渐下降;添加润滑剂后合金的脱模力明显降低,其温压脱模力较常压脱模力小;试样的抗拉强度、伸长率在润滑剂含量为0.6%时达最大值,这与烧结体的密度随润滑剂含量的变化一致;同时温压烧结坯的密度与常压试样的区别不明显,但抗拉强度和伸长率都高于同批的常压试样。     

Simulation of die wall friction‘s effect on density distribution in metallic powder compaction

1　ＩＮＴＲＯＤＵＣＴＩＯＮＤｉｅｃｏｍｐａｃｔｉｏｎｏｆｐｏｗｄｅｒｈａｓｂｅｅｎｕｓｅｄｉｎｃｏｍ ｐｏｎｅｎｔｓｍａｎｕｆａｃｔｕｒｉｎｇｉｎｄｉｆｆｅｒｅｎｔｆｉｅｌｄｓ[1～ 4 ] .Ｉｎｅｎ ｇｉｎｅｅｒｉｎｇａｐｐｌｉｃａｔｉｏｎｓ ,ｇｒｅｅｎｃｏｍ     

预混合工艺对铁基粉末冶金材料组织和烧结性能的影响

通过加入新型润滑剂制得Fe-2Cu-0.8C预混合铁基粉末,并制备了同成分机械混合粉末进行对比试验。对粉末流动性、松装密度以及压制性能进行了测试,并对烧结体的微观组织进行表征。结果表明:制备的预混合粉末流动性和松装密度均优于机械混合粉。当润滑剂加入量为0.6 mass%时,经600 MPa压力下压制所得的生坯密度为7.01 g/cm^3,烧结体密度为7.11 g/cm^3,批量压制时零件质量变化小于0.15%。通过预混合工艺,使得铜和石墨颗粒粘结到铁颗粒表面上,从而达到防止偏析和提高批次稳定性的目的。使用预混合粉末不仅提高了烧结体的尺寸精度和性能,同时可制备出更光洁的零件表面,进行形状复杂零件生产时更能体现出其在稳定性方面的优势。     

装粉方式对钛粉压制成形影响的数值模拟

用MSC.Marc软件模拟了3种不同装粉方式下钛粉压制成形过程中粉末的流动情况及压坯的密度分布规律.结果表明:粉末装粉方式对粉末压制过程及压坯密度有较大的影响,与平式装粉方式相比,采用凸式装粉,试样的烧结坯密度提高了6%,孔隙分布的均匀性也得到相应的改善.     

Experimental investigation of friction coefficient in tube hydroforming

The friction coefficient between tube and die in guide zone of tube hydroforming was obtained. In hydroforming, the tube is expanded by an internal pressure against the tool wall. By pushing the tube through tool, a friction force at the contact surface between the tube and the tool occurs. In guiding zone, the friction coefficients between tube and die can be estimated from the measured axial feeding forces. In expansion zone, the friction coefficients between tube and die can be evaluated from the measured geometries of expanded tubes and FE analysis.