已选分类
工学材料科学与工程
单选题在A-B二元固溶体中，当A-B对的能量小于A-A和B-B对的平均能量，该固溶体最易形成为______。
单选题Thermoplastic plastics are generally best for which of the following type of service conditions? A) impact B) creep resistance C) chemical exposure D) flammability
单选题体型高分子不可能出现______。
单选题在单元系的p(压强)-T(温度)相图内，当高温相向低温度相转变时体积收缩，则根据Clausius-Clapeyron方程，______。
单选题Which statement about fiber loading is not correct? A．the amount of reinforcement in a composite material B．is expressed in volume fraction C．a factor influencing the composite D．the strength of the composite is inversely proportional to the volume fraction of fiber present
单选题______ provides the substrate for CD-ROMs because they possess excellent optical properties as well as hardness and toughness. A．Polystyrene (PS) foam B．Polycarbonates (PC) C．Polyvinyl chloride (PVC) D．Polyethylene (PE)
单选题两平行螺型位错，当伯氏矢量同向时，其相互作用力______。
单选题The coordination number for the atoms in the fcc unit cell is______. A) 2 B) 6 C) 8 D) 12
单选题Recycling a thermoplastic polymer is possible, because ______ . A．different polymer chains in a thermoplastic are held together by relatively weak Van der Waals bonds which can be broken at relatively low temperatures B．thermoplastics are only lightly crosslinked in comparison to thermosets C．both of the above D．neither of the above
单选题Which of the following is the type ofbond between molecules of water? A) Ionicbond B) Covalentbond C) Hydrogenbond D) Metallicbond
单选题调幅分解(spinodal decmnposition)是经过______方式形成。
单选题在扩散系数的热力学关系中，称为扩散系数的热力学因子。在非理想混合体系中：
当扩散系数的热力学因子＞0时，扩散结果使溶质______；
当扩散系数的热力学因子＜0时，扩散结果使溶质______。
a．发生偏聚 b．浓度不改变c．浓度趋于均匀
单选题Which term describes the behavior of materials when subjected to some external force or condition? A) Material B) Property C) Automation D) Synthesis
单选题在晶体中形成空位的同时又产生间隙原子，这样的缺陷称为______。 (A) 肖特基缺陷 (B) 弗仑克尔缺陷 (C) 线缺陷
单选题现有下列铸铁：HT250、KTH350-10、QT600-2，请按用途选材。 A．制作机床床身，可选( ) B．制作柴油机曲轴，可选( ) C．制作汽车后桥外壳，可选( )。
单选题______，位错滑移的派一纳力越小。
单选题离子晶体通常借助表面离子的极化变形和重排来降低其表面能，对于下列离子晶体的表面能，最小的是______。
A.CaF2
B.PbF2
C.Pbl2
D.BaSO4
E.SrSO4
单选题Which advantage do smart polymeric materials offer designers? A) Eliminate selection problems B) Reduce raw materials costs C) Adapt to environmental changes D) Reduce processing
单选题泥浆胶溶必须使介质呈______，还必须有______价阳离子交换粘土中原来吸附的阳离子。
A.酸性
B.碱性
C.中性
D.一价
E.二价
F.三价
单选题Four quantum numbers characterize an electron as to its size, shape, and spatial orientation. The number ofenergy states for each orbital is determined by ______. A) The principal quantum number B) The second quantum number C) The third quantum number D) The fourth quantum number