钼钴对铸铁短纤维烧结体组织与性能的影响

本文研究了合金元素钼、钴对铸铁短纤维烧结体组织与性能的影响。钼使烧结体密度下降,孔隙率升高,组织由珠光体加铁素体变成贝氏体;当钼含量达到1.0％wt时,烧结体强度达到最大值1100MPa。钴明显加速烧结体致密化过程,提高了烧结体密度,组织中的铁素体随钴含量的增加而增加,当钴含量为3％时,烧结体强度达到最大值990MPa     

铬,铜对磷硼铸铁组织及性能的影响

在磷硼铸铁的基础上加入一定数量的合金元素铬和铜，可使大型铸件的组织得到细化，硬质相得到进一步强化，提高了大型铸件的机械性能     

超级多孔烧结金属

日本虹技公司运用高频振动切削法生产金属短纤维 ,材质包括铁、铜、铝及其合金 ,其标准尺寸是直径 30～ 90 μｍ、长度 2～ 6ｍｍ。金属短纤维的用途很广 ,包括制动垫之类摩擦材料以及作为耐火砖的增强剂等。传统工艺用金属短纤维制作的多孔烧结体 ,其气孔率在 2 0 %～ 80 %范围以内 ,是将金属纤维填充于模内加压成形后烧结制成。超级多孔烧结体的制造新工艺是使用毛绒状金属纤维 ,填充入模内后并不进行加压成形 ,而是进行烧结 ,通过根据纤维材质调整烧结温度和保护气氛等烧结条件从而得到最佳的烧结体。短纤维的材质有不锈钢、铜和铝等。在…     

合金元素对Cu-Zn-Si无铅黄铜组织性能的影响

在含铜65%的无铅硅黄铜中加入磷、镁、锆元素获取新型无铅铜合金。利用金相显微镜、SEM和EDS对其进行物相分析,通过拉伸试验、切削实验评价该合金的力学性能。结果表明,加入磷、镁、锆元素后合金中产生γ相,可改善切削加工性能的作用。其中同时加入磷、镁的合金组织均匀,具有较好的抗拉强度和切削性。     

合金元素在灰铸铁中的应用

一、合金元素的一般作用合金元素对灰铸铁组织的主要作用总结于表1。灰铸铁不希望有白口组织而影响切削加工。强的碳化物形成元素钒和铬具有大的白口倾向,因而必须严格地限制其加入量。铜和镍是石墨化元素,将其加入到硬度高的铸铁中可减少白口倾向,或者用于削     

铜锡低合金耐蚀铸铁蝶阀的研制

选用耐海水腐蚀蝶阀的材料，除耐蚀性能及制造成本外，还要考虑工厂的生产条件。我们已研制了铜锡低合金铸铁蝶阀，以取代生产成本高的高镍铸铁。1铸铁合金成成分的选择在海水中工作的阀门铸铁件（阀体、蝶板）通过铸铁合金化可提高其耐腐蚀性能，常用的合金元素有硅、铬、镍、铜、铝、锡和锑等。铜在铸铁中以其较高的正电极电位促使基体（阳极）钝化，降低腐蚀速率。在含2％Cu以下，铜量增加可以提高铸铁在海水中的耐蚀性。含铜铸铁中再加入锡或锑，能提高铸铁的析氢过电位，进一步提高其耐蚀性。表1所列为铜和锡对铸铁耐蚀性的影响，锡与…     

硼铸铁、稀土镁硼球铁缸套的初步实验

在汽车和拖拉机缸套生产中,国内部分正厂采用了中磷或高磷合金铸铁,也有的工厂采用含锡、锑、钼、铜等合金铸铁。高、中磷合金铸铁不但所要求的磷共晶网孔直径较小,在生产条件下难以达到,而且磷共晶的显微硬度     

铸铁短纤维结合剂金刚石圆锯片的研制

在研究成型、烧结工艺参数对铸铁短纤维烧结性能影响的基础上,研制新型金刚石锯片——铸铁短纤维结合剂金刚石圆锯片。在250 MPa,940℃条件下热压烧结10 min后,获得的金刚石锯片其刀头具有较高的密度(6.92 g/cm3)、强度和硬度,胎体对金刚石有较高的把持力,切削锋利,使用寿命偏短。制造铸铁短纤维结合剂金刚石工具,热压成形低温烧结工艺要优于冷压成形高温烧结工艺。     

Al—Zn—Mg—Sc系热强可焊铝合金

将钪加入Al-Zn-Mg系合金中，可显著改善该系合金的许多重要的技术特性和使用性能。01970和01975合金就是在Al-Zn-Mg系基础上发展起来的高强可焊热强铝合金。不含钪的Al-Zn-Mg系合金尽管含有多种过渡金属元素锆和钛，以及铜，并使锌和镁的成分最佳比，各含2.6%,从而使合金的可焊性增强，但由于铜的加入，使合金焊接时生成裂纹的倾向增大了。采用添加钪元素后，将使由铜引起的焊接裂纹倾向完全消失。由于采用钪合金化元素，还进一步保证了晶粒的细化，保证了该合金系即使在铜含量处于高位时，也具有较高的抗焊接热裂纹特性。现将01970和01…     

几种低合金铸铁的导热性

比较了几种低合金铸铁与HT200的导热性。指出：加入少量合金元素对铸铁导热性能影响不大；对于工作部位易发热升温而又对强度和耐磨性有一定要求的铸铁件，可选用低合金铸铁。     

Effect of Mg composition on sintering behaviors and mechanical properties of Al–Cu–Mg alloy

Al–3Cu–Mg alloy was fabricated by the powder metallurgy (P/M) processes. Air-atomized powders of each alloying element were blended with various Mg contents (0.5%, 1.5%, and 2.5%, mass fraction). The compaction pressure was selected to achieve the elastic deformation, local plastic deformation, and plastic deformation of powders, respectively, and the sintering temperatures for each composition were determined, where the liquid phase sintering of Cu is dominant. The microstructural analysis of sintered materials was performed using optical microscope (OM) and scanning electron microscope (SEM) to investigate the sintering behaviors and fracture characteristics. The transverse rupture strength (TRS) of sintered materials decreased with greater Mg content (Al–3Cu–2.5Mg). However, Al–3Cu–0.5Mg alloy exhibited moderate TRS but higher specific strength than Al–3Cu without Mg addition.     

Al2O3弥散强化铜-锡含油轴承的制备和性能

以内氧化法制备的Al2O3弥散强化铜(简称“弥散铜”)粉和雾化锡粉为原料,采用扩散合金化法制备弥散铜-锡合金粉末,经压制、烧结制备弥散铜-锡含油轴承,研究扩散温度对弥散铜-锡粉末合金化程度的影响,并考察烧结温度对含油轴承性能的影响。结果表明:弥散铜-锡混合粉末经700℃扩散处理后,锡在弥散铜基体中分布均匀,制备的弥散铜-锡合金粉末的松装密度为2.40 g/cm3、流动性为39.6 s(50 g);轴承压坯在800℃及以下温度烧结时,粉末颗粒之间没有发生显著烧结,导致轴承性能较差。当烧结温度为850℃时,粉末颗粒之间形成一定的冶金结合,轴承强度显著提升,开孔率小幅降低。在900℃及以上温度烧结时,轴承发生显著收缩,开孔率明显降低。850℃烧结制备的弥散铜-锡含油轴承的径向、轴向尺寸变化率均约为1.0%,压溃强度为160 MPa,显微硬度为166 HV0.05,开孔率为26.0%。     

Effects of rare earth addition on sintering process and dielectric property of cordierite based glass-ceramics

The effects of rare earth oxide on the sintering and dielectric property of cordierite-based glass-ceramics with non-stoichiometric composition prepared by quenching of molten droplets were investigated. The results show that the addition of rare earth oxide can lower the sintering temperature of cordierite glass-ceramics, improve the densification process and obviously reduce sintering activation energy. It is found that the densification of cordieritebased glass-ceramics is a liquid phase sintering process. The dielectric constant of the sintered compacts enhances with the increase of the density. When the sintering temperature is identical, the rare earth addition is found to have a noticeable effect on the dielectric loss of glass-ceramics. The properties of the glass-ceramics containing rare earth oxide appear to be correct for low firing temperature substrates.     

STRENGTHENING CAST IRON MATRIX BY ALLOYING ELEMENTS WITH POSITIVE AND NEGATIVE SEGREGATION

1.IntroductionAlloyingelementswereoftenusedtostrengthenthematrixofcastironsoastoobtainhighstrength,hardnessandgoodwearresistance.Thetraditionalideaistoachievefullpearlitestructllreandrefinethepearlitelamellarspacingl'-'].Alloyingelementsinfluenceaustenitestabi1ityindifferentways[5l6].Thusitisimportanttoselectandcombinealloy-ingelementswise1y.Useofpotenthardeningelements,whichsignificantlyrefinepearlitecombinedwithoneortwopearlitepromotionelementswasoftenrecommended,suchasCu Mo,Cu Cr Mo,Ni …     

Effect of heating mode and sintering temperature on the consolidation of 90W-7Ni-3Fe alloys

The present study compares the sintering response of 90W-7Ni-3Fe alloys consolidated in a 2.45 GHz microwave furnace and a conventional furnace. The W-Ni-Fe compacts were sintered in a temperature range of 1200-1500 °C corresponding to solid-state as well as liquid phase sintering. The compacts were successfully sintered in a microwave furnace with about 80% reduction in the overall processing time. For both the heating modes, the W-Ni-Fe alloys exhibited significant densification prior to melt formation through solid-state sintering. The in situ dilatometric studies revealed that the contribution to densification from solid-state sintering is higher at lower heating rates. In comparison to conventional sintering, microwave sintered compacts showed relatively refined microstructure and higher hardness and flexural strength.     

SINTERING BEHAVIOR OF Cu-AI ALLOY POWDER

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Warm compacted NbC particulate reinforced iron-base composite(Ⅱ)--Microstructure and properties

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Effect of Ni addition on the densification of TiC: A comparative study of conventional and microwave sintering

This study deals with the effect of conventional sintering and microwave sintering on the densification kinetics of Titanium Carbide (TiC) in the presence of Ni (1, 1.5, 2 wt%). TiC compacts were obtained after uniaxial pressing of powders synthesised by ball milling of Titanium and Carbon and sintering was done in the presence of Nickel. The samples prepared were subjected to conventional as well as microwave sintering. The XRD and SEM analysis were used for a study of the reaction of Ti and C powders upon addition of Ni, which reduced the sintering temperature to 1200 °C. The densification of TiC powders was due to the Ti-Ni eutectic system, the liquid phase formed at this temperature assisting the sintering process. The SEM images revealed the flake like structure of TiC in which the carbon diffused into Ti upon the addition of Ni, thereby supporting enhanced mass transfer. The XRD pattern showed the presence of Titanium Oxide (TiO₂) along with TiC which resulted in non-uniform distribution of hardness. Maximum hardness was achieved in the conventional sintered compacts which gradually increased with increase in Ni addition. The presence of the oxide phase and the formation of micro cracks resulted in non-uniform hardness for microwave sintered compacts. The maximum hardness of conventional sintered compact (375 HLD) was nearly 1.5 times more than the maximum hardness of the microwave sintered compact (250 HLD). The density of the microwave sintered compact was found to be higher by 8% than with the conventionally sintered compact.     

Cu、Mo对水平连铸球铁型材组织与力学性能的影响

在相同水平连铸条件下,采用合金化方法研究了不同Cu和Mo含量对φ60 mm球铁型材的基体组织与力学性能的影响.结果表明,加入一定量的Cu和Mo元素,可以获得珠光体型球铁组织或奥氏体-贝氏体型球铁,在Mo含量不变时,获得铸态奥氏体-贝氏体基体组织主要是由Cu含量决定.加入Cu和Mo元素后,球铁型材的抗拉强度、屈服强度和硬度均得到较大提高,但冲击韧度明显下降.     

Mechanical properties of β-SiC fabricated by spark plasma sintering

The consolidation of SiC nanopowder synthesized by the mechanical alloying method was subsequently accomplished by spark plasma sintering of 1700 °C for 10 min under an applied pressure of 40 MPa. The SiC sintered compact with relative density of 98% consisted of nano-sized particles smaller than 100 nm. This phenomenon resulted in the ordering process of stacking disordered structure formed by mechanical alloying. In this work, the effect of grain size and relative density on the mechanical properties were studied. The mechanical properties of sintered compacts were evaluated and compared with the reference samples fabricated from the commercial SiC powder (β-SiC, 0.3 μm, IBIDEN Co., Gifu, Japan) with sintering additive (B–C mixture). The Vickers hardness and bending strength of those sintered compacts increased with the increment of the density. However, the mechanical properties were lower than those of reference samples in case of lower density, even though the mechanical property was close to that of reference sample in case of higher density. This phenomenon was considered for the difference of bond strength between grains because those sintered compacts were fabricated without any sintering additives, while those reference samples were fabricated by accelerating the grain bonding with a sintering additive of B–C mixture. In other words, those results indicated that the effect of sintering additive affected on mechanical properties directly. This paper was presented at the International Symposium on Manufacturing, Properties, and Applications of Nanocrystalline Materials sponsored by the ASM International Nanotechnology Task Force and TMS Powder Materials Committee on October 18–20, 2004 in Columbus, OH.