SiCp/ZA27复合材料的制备及其力学性能

探讨了半固态机械搅拌法制备SiCp/ZA2 7复合材料的工艺 ,以及SiCp含量、大小对复合材料抗拉强度和硬度的影响 ,并对其抗拉断口进行了SEM分析。结果表明 :用该工艺可制得SiCp分布较均匀的锌基复合材料 ,其强度随SiCp含量、粒度的增大而减小 ;经SEM分析 ,其断口呈部分韧性断裂 ,且断裂机制因SiCp含量、大小的不同而不同 ;当复合材料中V(SiCp) <5 %时 ,其硬度值随加入量的增加而升高 ,当V(SiCp) >5 %时 ,随含量增加而降低 ,且小颗粒SiCp增强复合材料的硬度比大颗粒的要高     

Joining of SiCp/Al composites by insert powder layers

Mixed Al-Si, Al-Si-SiC and Al-Si-W powders were employed as insert layers to reactive diffusion bond SiCp/6063 MMC. The results show that SiCp/6063 MMC joints bonded by the insert layer of the mixed Al-Si powder have a dense joining layer with a typical hypoeutectic microstructure. Using mixed Al-Si-SiC powder as insert layer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregations, however, there are a number of porous zones in the joining layer, which results in the low shear strength of the joints, even lower than that of joints reactive diffusion bonded by the insert layer of mixed Al-Si powder. The W added into the insert layer of Al-Si-W nearly all reacts with Al to form intermetallic WAl12 during bonding. The reaction between the W and Al facilitates to form a dense joint of high quality, and the formed interrnetallic WAl12 has a reinforcing effect on the joints, which lead to the high shear strength of the joints. In general, under the condition of fixed bonding time （temperature）, the shear strengths of the joints increase as the bonding temperature （time） increases, but tend to a maximum at bonding temperature of 600℃ （time 90 min）.     

SiCp/LD2复合材料焊缝组织及性能

采用Al—Mg及Al-Si两种焊丝分别对SiCp／LD2复合材料进行了MIG焊，利用光镜、电镜及MTS-810试验机对焊缝的组织及性能进行了分析，结果表明，采用Al-Mg焊丝焊接时，熔池中Al—SiC间的界面反应程度均较大．生成了较多的针状Al4C3，且Al4C3的尺寸较大。采用Al-Si焊丝时，MIG焊熔池中的界面反应程度显著降低，仅生成了少量尺寸较小的针状Al4C3；利用Al—Si焊丝还可有效地防止焊缝熄弧处的宏观结晶裂纹。力学性能试验表明，用Al-Si焊丝焊接的接头强度比用Al—Mg焊丝焊接的接头强度高。     

不同热处理下滑动速度对SiCp/Al复合材料摩擦学性能影响研究

SiCp/Al复合材料非匀质性微观结构使其摩损机制较传统匀质材料更为复杂,不同工况及热处理工艺下复合材料的摩擦学性能也存在差异。以SiCp/2024Al复合材料为研究对象,进行球-面接触干滑动摩擦磨损实验,探究它在不同热处理状态及滑动速率下的摩擦磨损性能及磨损机制。结果表明:热处理对复合材料力学性能和摩擦学性能有显著影响,固溶+人工时效态复合材料具有更高的强度、硬度及耐磨性;滑动速度影响复合材料的表面接触性质及磨损程度,摩擦因数和磨损量随滑动速度提高逐渐增大;随滑动速度增加,复合材料主要磨损机制由剥层磨损向磨粒磨损转变,而磨损机制的转变明显加快了复合材料的磨损,在实际应用中应尽量避免此现象发生。     

Material deformation and removal mechanism of SiCp/Al composites in ultrasonic vibration assisted scratch test

The material removal process of SiCp/Al composites is a result of synergetic deformation and interaction among Al matrix, SiC particles and interface. The non-homogeneity of microscopic mechanical properties due to the inherent polyphase heterogeneity of SiCp/Al composites will directly affect the removal mechanism and surface integrity in the machining process. This paper aims to gain further insight of the material deformation and removal mechanism of SiCp/Al composites in ultrasonic vibration assisted machining process. The elastic modulus and hardness of SiCp/Al composites were determined through the indentation test by loading on Al matrix and SiC particles, respectively. Due to the interaction effects of the three phases during the deformation process, when the indenter is on a single phase, the influence of the other phases cannot be neglected and is reflected in the P-h curves. Scratch force, friction coefficient and material removal behavior were investigated in traditional scratch (TS) and ultrasonic vibration assisted scratch (US) tests. In most cases, with the assistance of ultrasonic vibration, scratch force and friction coefficient in US process are smaller than those in TS process, and the reduction of them is modeled and analyzed. The material removal behavior of SiCp/Al composites is similar to metal at the macroscale, and a high material removal rate is achieved in US process. SiC particles tend to maintain the structural integrity rather than be fractured or pulled out in US process. The scratched surface in TS process is damaged to a greater degree than that subjected to US process.     

复合玻璃钎焊高体分SiCp/6063Al复合材料的工艺及性能研究

使用PbO-B2O3-ZnO体系非晶玻璃钎料和PbTiO3晶体制成的复合玻璃钎料,辅助以阳极氧化和热压烧结工艺,在空气中实现了60vol.%SiCp/6063Al复合材料的钎焊连接。通过DSC、XRD和EDS等分析手段,研究了温度、时间对钎焊接头的影响。结果表明：母材的阳极氧化、钎焊温度的升高和保温时间的延长可以一定程度上提高接头的强度。当钎焊温度450℃,保温时间30min时,钎焊接头的压剪强度为33MPa。在钎焊过程中母材的氧化膜溶解于钎料,同时Al元素微量扩散,形成复合材料形式的焊缝。     

Microstructure evolution of Si3N4/Si3N4 joint brazed with Ag–Cu–Ti + SiCp composite filler

The Si₃N₄ ceramic was brazed by Ag–Cu–Ti + SiCp composite filler (p = particle) prepared by mechanical mixing. Effects of the content of Ti and SiC particles on microstructure of the joint were investigated. A reliable Si₃N₄/Si₃N₄ joint was achieved by using Ag–Cu–Ti + SiCp composite filler at 1173 K for 10 min. A continuous and compact reaction layer, with a suitable thickness, forms at the Si₃N₄/braze interface. The SiC particles react with Ti in the brazing layers, forming Ti₃SiC₂ thin layers around the SiC particles themselves and Ti₅Si₃ small particles in the Ag[Cu] and Cu[Ag] based solid solution. The higher content of SiC particles in the filler (≥10 vol%) depresses interfacial bonding strength between the Si₃N₄ substrate and composite brazing layer due to the thinner reaction layer and the bad fluidity of the filler. The Ti₃SiC₂ → TiC + Ti₅Si₃ reaction occurs when Ti concentration around SiC particles in the filler increases.     

热压ZTM／SiCp陶瓷复合材料活性氧化的初步研究

研究了在氧含量较低的条件下，热压ＺＴＭ／ＳｉＣｐ陶瓷复合材料活性氧化的问题，结果显示；在活性氧化的过程中，材料表面的形貌随氧化温度的升高而变化，最终形成非保护的氧化膜；活性氧化程度随氧化温度的升高而加剧，造成材料内部结构的损伤，使材料的力学性能大幅度下降。     

电参数对SiC_p/Al复合材料电火花深小孔加工的影响

采用电火花内冲液加工方式,分别研究了开路电压、伺服参考电压、电容及电流等电参数对45%SiCp/Al与Al2024合金深小孔加工效率、电极损耗及加工孔径的影响。结果表明:当电源放电能量越大、放电频率越高时,加工效率越高,且电极损耗越大;而在相同加工条件下,SiCp/Al的加工效率和电极损耗都明显高于Al2024合金,且开路电压和电容对SiCp/Al孔径的影响较大。     

复合铸造与振动斜板冷却铸造SiCp增强A356复合材料显微组织与耐磨性的比较

利用复合铸造和振动斜板铸造2种方法铸造SiCp增强A356复合材料,比较2种复合材料中碳化硅含量对材料显微组织、孔隙、硬度和耐磨性的影响。在铸态条件下,振动斜板铸造和复合铸造的2种复合材料的基体分别为球形和枝晶结构。振动斜板铸造的复合材料其碳化硅颗粒分布更加均匀,并且具有更高的硬度,复合铸造的材料则具有更少的孔隙。对于这2种复合材料,碳化硅颗粒的增加(体积分数最大为20%)导致碳化硅颗粒在基体合金内更加均匀分布并且提高了其耐磨性。与复合铸造材料相比,对于振动斜板铸造的复合材料,碳化硅含量的增加,将降低球形颗粒的尺寸和形状因子,并且具有较好的耐磨性。振动斜板铸造材料比复合铸造材料具有更好的力学性能,这是因为基体中的碳化硅颗粒分布更加均匀,而且振动斜板铸造过程中形成了球形组织。