SiCP混杂对C/Al浸渍成型复合材料性能的影响

碳纤维经混杂SiC_P后用压力浸渍成型方法制备成C/Al复合材料,分析混杂的SiC_P对C/Al复合材料力学性能的影响。测试了制备成的复合材料性能,并用SEM对复合材料断面组织与断口形态进行分析。结果表明,混杂的SiC_P可以分隔纤维,有利浸渍,使纤维分布均匀从而提高了复合材料的性能,而用sol-gel方法涂复SiC层并混杂SiC_P可获得最佳的性能。     

SiCP/Al复合材料的拉伸性能

对高体积分数碳化硅颗粒增强铝基(SiC_P/Al)复合材料的拉伸强度进行了试验研究。发现在较高应力水平下经过2次卸载的试件与未做卸载的试件相比,拉伸强度变化很小,说明加载-卸载过程对材料的拉伸强度影响不大。在试验研究的基础上,使用ANSYS软件建立了有限元模型,对SiC_P/Al复合材料的拉伸特性进行了仿真模拟。研究结果表明,低体积分数SiC_P/Al复合材料的力学性能更接近塑性材料;而高体积分数SiC_P/Al复合材料的力学性能则接近于脆性材料。拉伸强度模拟计算误差非常小,基体破坏是导致高体积分数SiC_P/Al复合材料破坏的主要因素。     

挤压铸造法制备可变形SiCP/Al复合材料的组织与性能

通过在SiC颗粒预制块中加入铝粉的方法制备了颗粒含量可控的SiC颗粒预制块,并用挤压铸造法制备了可变形SiC_P/Al复合材料。通过对颗粒体积含量为25%的SiC_P/Al复合材料进行热挤压变形,研究了挤压变形的可行性及其对复合材料组织与性能的影响规律。实验结果表明,用本文中提出的新工艺制备的25vol%SiC_P/Al复合材料可以成功地进行挤压比为25∶1的热挤压变形,并且热挤压变形可以明显提高复合材料的强度、刚度和塑性。     

Al2O3/TiB2/SiCw三元复合材料的力学性能及显微结构

以Al₂O₃为基体,SiC晶须和TiB₂颗粒两种增韧剂,采用热压烧结工艺制备了Al₂O₃/TiB₂/SiC_w三元复合陶瓷材料。研究了热压工艺参数对材料致密度的影响和晶须含量对该复合材料的力学性能和显微结构的影响。结果表明;随晶须含量的增加,该复合材料的热压温度和保温时间需要相应的增加;晶须拔出、裂纹偏转和晶须的桥接为该复合材料的主要增韧机理;随晶须含量的增加,该材料的室温断裂韧性增加;该材料的断裂韧性随温度的升高而呈增大趋势,并且晶须含量越高,材料的高温断裂韧性增幅越大。     

增强体SiCP对SiCP/Al复合材料腐蚀行为的影响

通过周期浸润腐蚀实验研究了不同SiC颗粒尺寸(70、90、140、220μm)和不同SiC颗粒体积分数(42%、49%、55%)的SiC_P/Al复合材料在酸性环境中的腐蚀行为。采用失重法、金相显微镜、X射线衍射仪以及扫描电镜分别计算腐蚀速率、观测微观组织、分析腐蚀产物的物相组成以及观察表面形貌。结果表明：腐蚀前期,SiC_P/Al复合材料的耐腐蚀性能随着颗粒尺寸的减小而降低,腐蚀中后期,耐蚀性能随着颗粒尺寸的减小反而有一定程度的提高;SiC颗粒的存在一方面促进了点蚀的成核,另一方面又打断了基体的连续性,改变了点蚀的生长方式,抑制了点蚀的进一步扩展;SiC_P/Al复合材料的耐腐蚀性能随着颗粒体积分数的提高而降低,其腐蚀产物主要为氧化铝和非晶态硫酸铝化合物。     

纳米SiC晶须和SiC颗粒混合增韧ZrB2陶瓷性能

分别采用纳米SiC晶须(SiC_W)、SiC颗粒(SiC_P)及SiC_W与SiC_P共同增韧ZrB₂陶瓷,在1950℃、20 MPa压力、氩气气氛下热压烧结制备了致密的SiC/ZrB₂陶瓷材料。研究了SiC_W和SiC_P的添加量对于SiC/ZrB₂陶瓷材料的显微结构、力学性能的影响,并分析了SiC_W和SiC_P对ZrB₂陶瓷力学性能影响的协同作用和增韧机制。结果表明：含15 vol% SiC_W 的复合材料的韧性达到8.08 MPa·m1/2,含15 vol% SiC_P的复合材料的韧性达到8.515MPa·m1/2,共同添加15 vol% SiC_W和15 vol%SiC_P的复合材料的韧性最高达到9.03 MPa·m1/2。SiC/ZrB₂复合材料强度和韧性提高的原因在于SiC_W和SiC_P抑制ZrB₂晶粒长大,促进ZrB₂的致密化,此外,SiC_W和SiC_P的协同作用也有助于材料韧性的提高。     

稀释中间复合材料法制备SiCP/356Al的研究

本文探索了一种制备SiC_P/Al的新工艺方法,即稀释中间复合材料法,以避免通常用来制备SiC_P/Al的复合铸造法中存在的浸润性差、气孔率高、存在氧化夹杂及颗粒偏聚等问题。结果表明,用该法能成功地制备10vol%和15vol%SiC_P/Al复合材料,其拉伸性能比用复合铸造法制备的同样材料高10%,且气孔率显着降低,X-rays衍射和TEM分析结果表明,该工艺过程中没有发生明显的界面反应,工艺参数的选择是合理的。     

SiCP/ZA27复合材料界面微结构分析及高温蠕变性能

利用透射电镜分析和高温持久硬度试验,研究了SiC_P/ZA27复合材料界面微结构和高温蠕变性能。结果表明,SiC_P/ZA复合材料具有较好的高温蠕变性能。对其试样进行微观分析,基体中的η相和增强相SiC_P都能显著提高ZA27合金的高温蠕变性能。     

原始SiC颗粒表面及SiCP/Al复合材料界面化学状态的研究

本文采用X射线光电子谱(XPS)和俄歇能谱技术(AES)对原始SiC颗粒表面和粉末冶金法制备的SiC_P/Al复合材料界面的化学状态进行了研究.结果表明:原始SiC颗粒表面主要存在SiC、SiO₂、游离C、吸附氧、Fe₂O₃等;SiC_P/Al复合材料界面存在Mg偏聚和氧元素.由热力学分析可知,Mg元素能够向界面偏聚,并可能与界面处的氧反应生成MgO.     

液-固两相区压缩变形对SiCw/6061Al复合材料组织和性能的影响

研究了液固两相区压缩变形对SiC_w/6061A l 复合材料组织和性能的影响。结果表明, 压缩变形温度对变形后复合材料中晶须长径比、取向, 复合材料组织的致密性、均匀性和界面结合状态均有不同程度的影响。复合材料组织的变化又影响到复合材料的性能。复合材料高温大变形后性能的变化是评价复合材料高温塑性成形加工工艺的最重要指标。通过分析复合材料的组织和性能, 从而确定了复合材料最佳压缩变形工艺。     

Study of Physical Properties of SiCw/Al Composites During Unloaded Thermal Cycling

The thermal expansion coefficient of SiCw/Al composites squeeze cast during unloaded thermal cycling was determined and analyzed. The study had shown that the thermal expansion coefficient of SiCw/Al composites reduced greatly with temperature raising. The thermal expansion coefficient of artificial ageing treatment SiCw/Al composites during unloaded thermal cycling reduced gradually, while the thermal expansion coefficient of squeezing SiCw/Al composites increased gradually. In addition, the thermal expansion coefficient of SiCw/Al composites reduced drastically with fiber fraction increasing.     

Synergistic enhancement of thermal conductivity between SiCw and h-BN in MVQ-based composite

Thermally conductive and electrically insulating h-BN/MVQ and h-BN/SiCw/MVQ composites were prepared by internal mixing and two roll mixing, using 1-dimensional (1D) silicon carbide whiskers (SiCw) and 2-dimensional (2D) hexagonal boron nitride flakes (h-BN) as fillers, and methyl vinyl silicone rubber (MVQ) as polymer matrix. Surface modification of 1?D SiCw and 2?D h-BN was characterized by Fourier transform infrared spectroscopy (FT-IR) and contact angle analysis. Morphology, thermal conductivity and dielectric constant of h-BN/MVQ and h-BN/SiCw/MVQ were studied. The results indicated that surface modified h-BN and SiCw could be uniformly distributed in MVQ matrix. At the same volume filler loading, thermal conductivity of h-BN/SiCw/MVQ ternary composite was higher than that of h-BN/MVQ binary composite. When part of 2?D h-BN was instead of 1?D SiCw, there was synergistically enhanced effect between 1?D SiCw and 2?D h-BN for thermal conductivity. When volume ratio of h-BN/SiCw was 8/2, thermal conductivity of h-BN/SiCw/MVQ was higher than that of other ratio. Thermal conductivity of h-BN/SiCw/MVQ composite with different volume ratio was linearly fit with Agari’ model.     

熔渗温度对Si/Al复合材料组织及性能的影响

采用无压熔渗法制备Si/Al复合材料,研究了熔渗温度对所制备Si/Al复合材料Si相形貌的影响,对Si相间基体合金的凝固组织进行了分析,测试了Si/Al复合材料热膨胀系数、热导率及抗弯强度。结果表明,在相同熔渗时间下,随着熔渗温度升高,所制备Si/Al复合材料中Si相从颗粒状到形成网络状。Si相间的Al-Si基体合金中不再是典型的初生相和共晶组织,而是出现了类似离异共晶的结晶现象,即初晶Si和共晶Si是在原存的Si相上结晶长大。XRD分析显示在所制备复合材料中只有Si相和Al相。随着熔渗温度升高复合材料热膨胀系数、热导率以及抗弯强度均出现下降。     

Fabrication process and thermal properties of SiCp/Al metal matrix composites for electronic packaging applications

The fabrication process and thermal properties of 50–71 vol% SiC_p/Al metal matrix composites (MMCs) for electronic packaging applications have been investigated. The preforms consisted with 50–71 vol% SiC particles were fabricated by the ball milling and pressing method. The SiC particles were mixed with SiO₂ as an inorganic binder, and cationic starch as a organic binder in distilled water. The mixtures were consolidated in a mold by pressing and dried in two step process, followed by calcination at 1100 °C. The SiC_p/Al composites were fabricated by the infiltration of Al melt into SiC preforms using squeeze casting process. The thermal conductivity ranged 120–177 W/mK and coefficient of thermal expansion ranged 6–10 × 10^–6/K were obtained in 50–71 vol% SiC_p/Al MMCs. The thermal conductivity of SiC_p/Al composite decreased with increasing volume fraction of SiC_p and with increasing the amount of inorganic binder. The coefficient of thermal expansion of SiC_p/Al composite decreased with increasing volume fraction of SiC_p, while thermal conductivity was insensitive to the amount of inorganic binder. The experimental values of the coefficient of thermal expansion and thermal conductivity were in good agreement with the calculated coefficient of thermal expansion based on Turner's model and the calculated thermal conductivity based on Maxwell's model.     

粉末冶金法制备SiC_p/Al_2W_3O_(12)/Al复合材料及其热膨胀性能

通过添加适量的Al_2W_3O_(12)负热膨胀粉体来优化碳化硅颗粒增强铝基(SiC_p/Al)复合材料的热膨胀系数。实验采用固相法制备负热膨胀性能的Al_2W_3O_(12)粉体,并按10%,20%,30%的体积比添加至SiC_p/Al复合粉体中,利用粉末冶金工艺制备SiC_p/Al_2W_3O_(12)/Al复合材料。实验结果表明:制备的复合材料组织分布均匀,致密度良好。室温到200℃内,在Al基体质量分数不变的前提下,Al_2W_3O_(12)的加入有效降低了复合材料的热膨胀系数。     

AlN添加量对BN基复合陶瓷热学性能与抗热震性的影响

以BN、SiO₂、AlN为原料, 采用热压工艺制备出BN基复合陶瓷。研究了AlN添加量对复合陶瓷热学与抗热震性能的影响。结果表明: 随着AlN添加量的增加, 复合陶瓷的热膨胀系数呈现先降低后升高的趋势。当AlN的添加量为5vol%时, 复合陶瓷的平均热膨胀系数最小, 为2.22×10^-6/K; 复合陶瓷的热导率则随着AlN添加量的增加呈先升高后降低的趋势, 当AlN的添加量为10vol%时达到最大值。未添加AlN的复合陶瓷热震后的残余强度随着热震温差的增大而升高; 随着AlN的引入, 复合陶瓷热震后的残余强度呈下降的趋势。对于添加5vol%AlN的复合陶瓷, 经1100℃热震后其残余强度为219.7 MPa, 强度保持率为88.9%, 抗热震性良好。     

SiC晶须增韧Al_2O_3及ZrO_2（Y_2O_3）基陶瓷复合材料的抗热震行

采用三点弯曲及扫描电镜等方法研究了ＳｉＣｗ／Ａｌ２Ｏ３、ＳｉＣｗ／ＺｒＯ３（Ｙ２Ｏ３）及ＳｉＣｗ／Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）陶瓷复合材料的抗热震性．结果表现ＳｉＣｗ的加入使Ａｌ２Ｏ３、ＺｒＯ２（Ｙ２Ｏ３）以及Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）基体的抗热震性显著提高，Ａｌ２Ｏ３陶瓷基复合材料的抗热震性明显优于ＺｒＯ２（Ｙ２Ｏ３）陶瓷基复复合材料．同时发现在Ａｌ２Ｏ３十ＳｉＣｗ材料基础上再加入少量ＺｒＯ２（２Ｙ）颗粒（１０Ｖｏ１％），也可进一步提高Ａｌ２Ｏ３＋ＳｉＣｗ材料的抗热震性．     

复合型散热硅橡胶研究

研究了氧化铝和氮化硼粒子用量对硅橡胶热膨胀系数、热稳定性及热导率的影响.发现加入两种填料均显著降低了橡胶热膨胀系数,提高了热稳定性及热导率;试验测试热导率和理论计算值差距较大,用Agari模型分析了两种填料对硅橡胶热导率差异影响的原因.按照一定比例混合这两种填料所得混合填料填充硅橡胶可获得最大热导率及较佳性能.所制备的复合硅橡胶具有很好的物理性能,是作为散热使用的弹性导热垫片的理想材料.     

Correlation between the thermal responses and microstructure patterns in aluminum‐based silicon carbide composites (SiCp/Al) consolidated by different high pressure torsion schemes

High pressure torsion of powder mixture is a novel strategy for manufacturing high‐quality aluminum‐based silicon carbide composite SiC_p/Al billet used in electronic packaging, however, the correlation between thermal properties and the high pressure torsion process and the related mechanisms are still unclear. To this end, the variation rules of thermal expansion coefficient and thermal conductivity with high pressure torsion turns are studied and the corresponding microstructure morphology and dislocation patterns are observed by optical and transmission electron microscopes. The results show that thermal expansion coefficient decreases monotonically but thermal conductivity first increases then decreases with the increase of high pressure torsion turns. Moreover, the results of differential scanning calorimetry experiments indicate the decrease of recrystallization temperature with turns of high pressure torsion. The non‐monotonic variation of thermal conductivity is attributed to the combined effect of the improved relative mass density brought by the consolidation effect and the dislocation tanglement and pattern transformation (formation of in‐situ sub‐grains) during high pressure torsion process.     

放电等离子烧结制备Diamond/Al复合材料

采用放电等离子烧结法（SPS）制备了Diamond/Al复合材料,研究了金刚石粒径、成分配比、工艺参数等对复合材料的导热性能的影响。结果表明,SPS可以得到导热性能较好的Diamond/Al复合材料,致密度是影响该材料导热性能的最重要因素。在实验确定的金刚石体积分数50%,金刚石粒径70 μm,温度550℃、压力30 MPa的工艺条件下,所制备的材料致密度较高,热导率为182 W/(m·K),比相同条件下纯铝粉烧结体的热导率提高了34.8%,表明金刚石的添加对烧结铝基材料导热性能有明显的改善作用。