Cu的添加方式对铁基预合金粉末与烧结体组织及性能的影响

采用扩散法制备Fe-4Ni-0.5Mo-1.5Cu预合金粉末,分别采用添加常规铜粉和改性超细铜粉的方式添加合金元素Cu。对制备的粉末进行压制与烧结,采用金相显微镜和扫描电镜(SEM)分析粉末与烧结体的组织与形貌,研究Cu元素的添加方式对Fe-4Ni-0.5Mo-1.5Cu预合金粉末及其烧结体组织和性能的影响。结果表明,预合金粉末中合金元素的分布状况影响烧结体的组织分布,进而影响烧结体的力学性能。以添加改性超细铜粉的方式加入合金元素铜时,预合金粉末中的铜元素分布均匀,压坯密度略有减小,但烧结体强度显著提高,抗拉强度和冲击能分别达到683.5 MPa和24.5 J,接近国外同类产品性能。     

共沉淀法制备Fe-Cu基预合金粉的低温热压烧结

采用共沉淀法制备含有Co、Ni、Sn元素的Fe-Cu基预合金粉,在此预合金粉中添加25%(质量分数)的WC作为骨架相,在700~860℃温度下真空热压烧结,获得金刚石工具用金属结合剂。利用X射线衍射(XRD)和扫描电镜(SEM)对预合金粉末及金属结合剂进行形貌观察与物相分析,并测定烧结体的硬度、抗弯强度及磨耗比等力学性能。结果表明,Fe-Cu基预合金粉已形成固溶体,实现了合金化,粉末粒度较细,约在3μm左右,表面较光滑,呈不规则状。Fe-Cu基预合金粉末的原子扩散及相变主要发生在820~846℃温度范围内,在820℃下热压烧结时效果最好,胎体孔洞缺陷少,具有最佳的物理与力学性能,硬度为113.9HRB,致密度达到98.86%,抗弯强度为1306.4 MPa,结合剂对金刚石颗粒的包镶能力最强。     

铜锡预合金粉热压性能研究北大核心

采用多级耦合雾化法制备的FCuSn15和FCuSn20预合金粉末为原料,在不同工艺条件下进行热压烧结,分析两种铜锡预合金粉末烧结体的致密度、洛氏硬度、三点抗弯强度及显微组织。结果表明,FCuSn20粉末烧结体相对FCuSn15粉末烧结体致密度略有下降,洛氏硬度提高约12%～15%,三点抗弯强度降低32%～36%;铜锡预合金粉末在烧结过程中表面反偏析形成液相的(α+δ)共析体,粉末颗粒重排获得最紧密的堆砌和最小的孔隙总表面积,促进烧结致密化;FCuSn20烧结体中形成较多的硬脆δ相,造成烧结体强度降低。     

Fe-Cu-Sn烧结体的显微组织与力学性能

分别采用水雾化Fe-30%Cu合金粉末和单质Sn、Fe、Cu元素粉末为原料制备Fe-Cu-Sn合金,研究原料粉末和Sn含量(质量分数)对Fe-Cu-Sn烧结体致密度、冲击韧性、硬度和抗弯强度的影响。结果表明:与采用元素混合粉末相比,采用合金化程度较高的Fe-30%Cu(质量分数,下同)合金粉末为原料能大幅提高850℃烧结的Fe-Cu-5%Sn合金的致密度和力学性能,其致密度由82.8%提高到94.3%,硬度、冲击韧性和抗弯强度分别提高52%、84%和109%;当Sn的质量分数w(Sn)为3%～15%时,随着Sn质量分数增加,合金的硬度增大,冲击韧性和抗弯强度先增加后减小,其中w(Sn)为5%时,其抗弯强度和冲击韧性都较高,分别为977 MPa和11.6 J/cm2。当烧结体为双重结构组织时,其力学性能显著提高。     

预混合法和预合金法制备Cu-Sn粉末的显微组织和烧结性能

使用预混合法和预合金法制备了Cu-Sn粉末,研究了Cu-Sn粉末在烧结过程中的显微组织和物相变化规律,同时测试了Cu-Sn粉末在不同温度条件下的烧结性能。实验结果显示,通过预混合法制备的CuSn10、CuSn20粉末烧结态组织由α相和α+δ共析组织组成,而预合金法制备的CuSn10粉末烧结态组织则由单一的α相组成。两种方法制备的粉末在相同条件下烧结后,预混合Cu-Sn粉末的烧结体相对于生坯产生了膨胀,预合金铜锡粉末烧结体则表现为收缩,且预合金Cu-Sn粉末烧结后的断裂强度、含油率和有效含油率均高于预混合粉末。     

超细CeO2粉末对铁基合金工具胎体组织性能的影响

以超细CeO2为添加剂,采用热压烧结工艺制备铁基金刚石工具胎体,并对金刚石工具胎体的组织与性能进行检测分析。结果表明:铁基预合金粉末中超细CeO2粉末的添加,使得烧结后胎体的相对密度与硬度提高,抗弯强度有所降低。并随CeO2粉末质量分数的增加,胎体组织致密化效果越好;而胎体硬度在CeO2质量分数为0.75%时,达到最大值300HV0.1。断口分析表明,添加CeO2粉末烧结后的胎体断口组织更均匀、细密,且随着CeO2含量的增加,韧窝逐渐变小,深度更浅。     

B4C对M3:2粉末冶金高速钢组织与力学性能的影响

本文以水雾化M3:2高速钢预合金粉末为原料,添加适量碳化硼(B4C)粉末颗粒,球磨混合均匀后,经700 MPa单向压制,1190℃和1230℃真空烧结,制备出了综合性能优良的粉末冶金高速钢(powder metallurgy high-speed steel,PM HSS)材料。通过示差扫描量热分析仪(differential scanning calorimeter,DSC)、X射线衍射仪(X-ray diffractometer,XRD)、电子探针显微分析仪(electro-probe microanalyzer,EPMA)、扫描电子显微镜(scanning electron microscope,SEM)和万能材料试验机等对烧结粉末冶金高速钢进行物相分析、显微结构观察和力学性能测试。结果表明,当添加体积分数为0.3%B4C时,M3:2粉末冶金高速钢的最佳烧结温度可降低约40℃;1190℃烧结温度下,添加体积分数为0.3%B4C的粉末冶金高速钢硬度为HRC 54.1,抗弯强度3074.09 MPa,与达到致密化时未添加B4C的粉末冶金高速钢相比,硬度提升3.6%,抗弯强度提升10.5%。加入的B4C粉末颗粒除了发挥烧结助剂的作用和降低烧结温度外,还会参与合金化,增强材料力学性能。     

添加亚微米Fe_2O_3对Fe-Ni-Cu-C粉末冶金材料组织与性能的影响

采用亚微米级Fe2O3粉末作为烧结助剂制备Fe-Ni-Cu-C预混合粉,考察Fe2O3颗粒在混合料中的分布状态、Fe2O3添加量对材料的成形与烧结密度以及显微组织和力学性能的影响。结果表明,亚微米Fe2O3粉末可均匀分布在预混料中,但当Fe2O3粉末添加的质量分数超过0.3%时材料的压制与烧结密度明显下降;添加少量的亚微米Fe2O3粉末可提高合金的力学性能,Fe2O3粉末的添加量为0.3%时,合金的强度、韧性和伸长率较未添加Fe2O3粉末时分别提高7.3%、5.8%和4.8%;由于亚微米Fe2O3还原成微细铁粉后具有高活性,坯体烧结时铁基颗粒间的烧结连接率增大,拉伸断口形貌呈较多的韧窝组织,且烧结体中的孔隙圆化。     

还原铁粉对Fe-1.1Ni-0.5Mo-0.5Cr合金组织与性能的影响

在惰性气体雾化法制备的Fe-1.1Ni-0.5Mo-0.5Cr预合金粉末中添加1.5％的Cu粉和0.6％的C粉(均为质量分数)以及还原铁粉(添加量分别为0、10％、20％和30％),混合均匀后在600 MPa压力下模压,在1 180℃烧结1h.烧结合金经180℃/1h回火处理后,进行密度、硬度、拉伸力学性能检测以及显微...     

超细W-25Cu粉末在金刚石工具中的应用研究

采用粉料混合、制粒、冷压成形和真空热压烧结法制备样品.利用SEM观察了添加超细W-25Cu合金粉末和W、Cu单质粉末的刀头断口金刚石形貌并进行了EDS分析,研究了烧结温度对添加超细W-25Cu合金粉和添加W、Cu单质粉末的胎体硬度、烧结密度、抗弯强度的影响,并利用SEM、金相和面扫描手段分析了断口形貌、显微组织和主要元素分布.结果表明:添加超细W-25Cu合金粉末的刀头中,金刚石表面形成了含W元素较多的“岛状”晶体物质并形成网状结构,提高了胎体对金刚石的把持力;在试验温度范围内,添加超细W-25Cu合金粉能显著提高胎体的硬度、致密度和元素分布的弥散性,但降低抗弯强度.锯片切割实验表明:添加超细W-25Cu合金粉比添加W、Cu单质粉可提高工具使用寿命约40％,可见添加超细W-25Cu合金粉末确实有利于胎体耐磨性的增加和胎体对金刚石把持力的提高.     

Iron based partially pre-alloyed powders as matrix materials for diamond tools

Abstract

The hardness and bend strength of diamond tool matrix materials prepared from partially pre-alloyed Fe–Cu powders and from elemental powder mixes of equivalent composition has been compared. After sintering at 890^oC, the hardness of the partially pre-alloyed powder matrix was 81.72?HRB, 9.3% higher than that of the mixed powders matrix; sintering at 870^oC gave the highest bend strength (634.85 MPa), 11.6% higher than that of the mixed powders matrix. The improved homogeneity of alloy elements distribution achieved in the matrix by pre-alloying was shown generally to increase the hardness and strength. The cutting performance of diamond tool segments prepared with the pre-alloyed matrix material met standard requirements; overall, the pre-alloyed material is felt to offer significant manufacturing and performance benefits.     

铜铁预合金粉末对铜基摩擦材料摩擦磨损性能的影响

利用粉末冶金方法制备了含不同质量分数铜铁预合金粉末的铜基摩擦材料,并在不同温度下对材料摩擦性能进行测试。结果表明:铜铁预合金粉末的引入使得铁元素在烧结后铜基体中及铜基体与其他组元界面处析出,阻碍了烧结,导致材料密度下降。存在于界面处的铁以及反应生成的珠光体成为硬质强化相,使得材料的磨损机理从纯铜基体时的黏着磨损向添加铜铁预合金粉末之后的磨粒磨损转变,导致摩擦系数先下降后上升。200～250 ℃为摩擦系数保持稳定的临界温度。当超过临界温度时,摩擦表面铜软化,其自润滑作用使得摩擦系数下降。含30%铜铁预合金粉末的铜基摩擦材料（质量分数）的摩擦磨损性能最佳,这是由于此时摩擦材料兼具铜良好的塑性以及生成的适量硬质相能够强化摩擦表面。     

不同配比铁基预合金粉的胎体性能研究

对湿法冶金工艺制备的两种铁基预合金粉(Fe_(43)Co_(24)Cu_(33)和Fe_(56)Co_(14)Cu_(30),以下简称A和B)进行了性能研究,对其粉末颗粒的形貌和氧含量进行了对比分析,并经过750、800、850、900、950℃五种烧结温度制备热压烧结试样。通过阿基米德排水法测定烧结试样密度,利用HR-150A型洛氏硬度计测量烧结试样的显微硬度,利用三点弯曲法测定烧结试样的抗弯强度,使用扫描电子显微镜观察烧结试样的断口形貌。结果表明:随着烧结温度的提高,两种烧结试样的密度都呈增加趋势,当温度超过850℃后,密度变化逐渐趋于平缓;烧结试样的硬度都随着温度的升高先增加后降低,烧结试样B硬度在850℃以前要高于烧结试样A,且在800℃时达到最大值,当温度高于850℃时烧结试样A的硬度要高于烧结试样B;两烧结试样的抗弯强度都随温度的升高而增大;预合金粉A的烧结试样对温度敏感性较小,当温度达到850℃以后,晶粒几乎不在长大,预合金粉B的烧结试样对温度敏感性比较大,随着温度的升高,晶粒不断地长大。     

Production and properties of brass-base P/M constructional materials. A review

Conclusions The best processing properties are exhibited by brass powders manufactured by the diffusional impregnation technique, using a zinc powder, brass swarf, or a copper-zinc master alloy as a point source. However, as this is a very labor-intensive process, normally preference should be given to melt atomization as a method of manufacture of brass powders. Brass P/M parts produced by the conventional method consisting of pressing a powder and sintering the resultant compacts have porosities of not less than 7–10%, and consequently this method is not widely used for the production of constructional brass parts. The sintering of compacts from copper and copper-zinc master alloy powders gives more stable zinc contents compared with the sintering of compacts from copper and zinc powders; the greatest stability of chemical composition is exhibited by sintered compacts from a homogenized brass powder. The formation of diffusional porosity accompanying the evaporation of zinc may be prevented by performing sintering in the presence of a liquid phase (which appears in the presence of a phosphorus or lead addition), saturating the sintering atmosphere with zinc vapor, and adding carbonates or halides of alkali and rare-earth metals to starting powders. The mechanical properties of materials can be markedly improved by eliminating their porosity. This may be achieved by subjecting porous preforms to hot forging, which enables brass P/M parts to be obtained whose mechanical properties are comparable to those of cast parts.Translated from Eoroshkovaya Metallurgiya, No. 3(255), pp. 56–64, March, 1984.     

预扩散处理对原位生成TiC_p/Fe基粉末冶金复合材料组织与性能的影响

将水雾化Fe粉与Ni粉、Mo粉、Ti粉混合均匀,然后在800℃、50%H2+50%Ar(体积分数)气氛保护下进行预扩散处理,将预扩散粉与电解Cu粉和石墨粉混合,通过压制与烧结,制备Ti C颗粒增强Fe基复合材料。通过X射线衍射分析、扫描电镜及能谱分析和力学性能测试等手段,研究预扩散处理对原位生成Ti Cp/Fe基粉末冶金材料组织与性能的影响。结果表明:Fe-Ni-Mo-Ti混合粉在800℃下预扩散处理后形成表面粗糙的团球状预扩散粉末颗粒,但合金元素在Fe粉颗粒内分布不均匀。与用混合粉制成的Ti Cp/Fe基复合材料相比,用预扩散粉制备的材料孔隙率略有增加。随预扩散时间延长,材料中富Ti区的尺寸减小,组织明显细化,珠光体分布更均匀,同时形成大量弥散分布的粒径在0.1~0.5μm的Ti C颗粒。材料的硬度和抗弯强度都随原料粉预扩散时间延长而提高,用60 min预扩散粉制成的Ti Cp/Fe基复合材料的硬度HRB和抗弯强度分别达到63.6和613.7 MPa,比用混合粉制成的Ti Cp/Fe基复合材料分别提高11.8%和38.3%。用预扩散粉末制备的Fe基复合材料的断裂形式为具有一定韧性断裂特征的脆性断裂。     

粉末冶金工艺对纯铁软磁材料性能的影响

利用粉末冶金技术制备纯铁软磁材料,在不同温度和压力下将不同粒径铁粉压制成生坯,并在保护气氛下进行烧结。结果表明:不同粒径铁粉混合有助于压坯密度的增加,适宜的压制温度可以有效地促进粉末流动,避免大尺寸孔洞的形成,优化组织。140℃、800 MPa温压条件下雾化铁粉压坯密度最高可达7.35 g·cm-3。对比常温压制,温压压坯烧结后孔洞分布均匀。烧结体密度随温度的升高而上升,雾化铁粉压坯在1250℃烧结后密度最高可达7.47 g·cm-3。在一定范围内,软磁材料磁性能与密度成正比,混粉压制试样的密度接近理论值,但在混合铁粉中,较细的铁粉夹杂于粗粉中,阻碍磁畴壁移动,造成饱和磁化强度（M_s）偏小、矫顽力（H_c）偏大的现象,M_s为205.51 emu·g-1,Hc为7.9780 Oe。     

高能球磨对新型TiC钢结硬质合金组织和性能影响的研究

采用行星式球磨机对Fe-3.0Cr-3.0Mo-0.5Cu-0.5C-33TiC新型钢结硬质合金混合粉末进行高能球磨,对不同球磨时间粉末的形貌和粒度进行观察,测定了烧结后合金的密度、硬度和抗弯强度,并对其组织结构进行了分析.结果表明：球磨初期,粉末粒度迅速减小,粉末出现片状形貌,随着球磨时间增加,粉末粒度减小速度变缓,最后趋于稳定,片状形貌逐渐消失,不规则球形形貌增多.球磨过程中,Fe与其它添加元素（C、Mo、Cu）发生合金化反应.在一定时间内,随着球磨时间的增加,混合粉末成分均匀性增加,合金的密度、硬度和抗弯强度也明显提高.     

Characterization,Physical and Mechanical Behavior of Sintered Atomized Iron–Zinc Stearate Composite

Powder metallurgy is an effective method to process the iron component in near net shape. In this paper, the influence of particle size, lubricant and compaction load on the physical and mechanical properties of the sintered iron–zinc stearate composite sample has been investigated. Atomized iron powders of particle size 100–200 and 200–300 mesh with zinc stearate 2.5, 5.0 and 7.5 wt% were used for preparing the samples. Green samples were prepared by cold compaction at various loads of 200, 180 and 160 KN and the sintering is done at 500 °C. The physical properties and the mechanical properties such as density, hardness and compression strength have been measured for the sintered samples. Scanning electron microscope was used to characterize the atomized iron powders and the sintered samples. It were confirmed that the shape of atomized iron powder particles were irregular, dendritic and acicular. Energy dispersive spectroscopy was used to identify the elemental compositions of powders and the sintered samples. Taguchi (L₁₈) method was effectively used to develop the regression model and describe the contribution of the input parameters in compressive strength, density, and hardness. The highest effect on density was powder particle size followed by compaction load and lubricant wt%. The Hardness value increased with increase in the powder particle size and compaction load and decreases with increase in the lubricant wt%. The compression strength increased with increase of compaction load and decrease of lubricant wt% and particle size.     

Sintered copper–graphite powder compacts forindustrial applications

Abstract

Studies were made on copper/graphite based powders and sintered compacts for industrial applications. The dependence of particle shape on friction in the powder mass, compression ratio, and electrical receptivity of powder metallurgy components was studied using near spherical precipitated copper powders and angular or flakelike powders generated by mechanical comminution. Results reveal that powders with particles that are nearly spherical in shape have lower friction, lower compression ratios, and higher electrical resistivities in sintered compacts than powders with acicular or flakelike particles. Also, the effects produced by the small additions of lead and zinc (up to 2·5 wt-%) on the electrical resistivity and hardness of sintered copper–graphite compacts are also presented, and the influence of variation of briguetting pressure is discussed.