课程安排 绪论,力学性质 材料导论 聚合物材料 第三讲复合材料 第四讲陶瓷材料 第五讲金属学基础 第→章绪论 七讲材料与环境 第九讲磁性能,光学性质 课末考试60% What are materials 1986年奔驰汽车 1996年奔驰汽车 Materials are the matter of the universe. These substances have properties that make them useful in 钢铁:67% structures, machines, devices, products 高分子:12% 高分子:18% and systems. 合金铝:4% 金铝:6% 纺织品:12% 织品:12% 材料是宇宙间可用于制造有用 物品的物质。 材料成熟曲线 MATERIALS SCIENCE ENGINEERING 超级合金 involves the generation and 传统工程塑料 application of knowledge relating 高性能工程塑料 the composition, structure, and the 光导纤维 processing of materials to their 脂基复合材料 金属基复合材料 properties and uses. 材料组成、结构、加工与材料 性质、使用之间关系的发现与应用
1 材料导论 第一章 绪论 课程安排 第一讲 绪论，力学性质 第二讲 聚合物材料 第三讲 复合材料 第四讲 陶瓷材料 第五讲 金属学基础 课中考试 40％ 第六讲 金属材料 第七讲 材料与环境 第八讲 电性能 第九讲 磁性能，光学性质 课末考试 60％ What are materials? Materials are the matter of the universe. These substances have properties that make them useful in structures, machines, devices, products, and systems. 材料是宇宙间可用于制造有用 物品的物质。 钢铁：67% 高分子：12% 合金铝：4％ 纺织品：12％ 钢铁：62% 高分子：18% 合金铝：6％ 纺织品：12％ 1986年奔驰汽车 1996年奔驰汽车 材料成熟曲线 铝 铜 碳钢 通用塑料 不锈钢 超级合金 特殊金属 传统工程塑料 高性能工程塑料 工程塑料合金 光导纤维 树脂基复合材料 金属基复合材料 结构陶瓷 MATERIALS SCIENCE & ENGINEERING involves the generation and application of knowledge relating the composition, structure, and the processing of materials to their properties and uses. 材料组成、结构、加工与材料 性质、使用之间关系的发现与应用
WHY STUDY MATERIALS 原材料制取 SCIENCE AND ENGINEERING 丢弃/回收 预加工 Materials scientists and engineers are 材料环 specialists who are totally involved in the 服务期 工程化 investigation and design of materials. (生产制品 Does the material possess the WHY STUDY MATERIALS necessary mechanical, electrical, and SCIENCE AND ENGINEERING thermal properties? Can the material be formed to the desired Many times, a materials problem is one Will the properties of the material alter with of selecting the right material from the time during service? many thousands that are available. Will the material be adversely affected by the environmental conditions and resist corrosion and other forms of attack Will the material be acceptable on aesthetic Processing Will the material give sufficient degree of → Structure reliability and quality? Can the product be made at an acceptable cos → Performance Can the product b
2 WHY STUDY MATERIALS SCIENCE AND ENGINEERING Materials scientists and engineers are specialists who are totally involved in the investigation and design of materials. 原材料制取 预加工 生产制品 服务期 丢弃/回收 工程化 材料环 Many times, a materials problem is one of selecting the right material from the many thousands that arc available. WHY STUDY MATERIALS SCIENCE AND ENGINEERING Does the material possess the necessary mechanical, electrical, and thermal properties? Can the material be formed to the desired shape? Will the properties of the material alter with time during service? Will the material be adversely affected by the environmental conditions and resist corrosion and other forms of attack? Will the material be acceptable on aesthetic grounds? Will the material give sufficient degree of reliability and quality? Can the product be made at an acceptable cost? Can the product be recycled? Processing → Structure → Properties → Performance
Mechanical Subatomic structure Thermal A tomic level structure Electrical Structure Properties Physical Magnetic AcroscoPIc tical Macrosco Deteriorative METALS 金属材料 quite strong, yet deformable 材料 good conductors of electricity and heat 材料 半导体 not transparent to visible light 途料》分子材料 polished metal surface has a lustrous appearance The elements inherently metallic in nature Ceramics compounds between metallic and nonmetallic elements typically insulative to the passage of electricity and heat more resistant to high temperatures and harsh BEER environments hard but very brittle
3 Structure Subatomic structure Atomic level structure Microscopic Macroscopic Properties Mechanical Electrical Thermal Magnetic Optical Deteriorative Physical 材 料 金属材料 高分子材料 有色金属 粉末金属 钢铁 塑料 橡胶 涂料 粘合剂 纤维 复合 材料 陶 瓷 材 料 玻璃 结晶陶瓷 碳材料 半导体 METALS good conductors of electricity and heat not transparcnt to visible light; polished metal surface has a lustrous appearance quite strong, yet deformable The elements inherently metallic in nature Ceramics compounds between metallic and nonmetallic elements typically insulative to the passage of electricity and heat more resistant to high temperatures and harsh environments hard but very brittle
Ceramic compounds indicated by a combination of metallic elements with nonmetallic elements POLYMERS >Electrical insulation >Thermal insulation >Chemical resistance Extremely light weight >Transparency >Tough Colorability The elements associated with commercial polymers COMPOSITES A composite material is a combination of two or more chemically different materials having a distinct interface between them which act together to produce a desired HEEEBRMEIHISRER (tailored) set of properties 图EE A composite is designed to combine the best HaEEEERHEI characteristic of each constituent material EXAMPLES OF COMPOSITES SEMICONDUCTORS Semiconductors have electrical properties that are intermediate between the electrical conductors and insulators Furthermore, the electrical characteristics of these materials are extremely sensitive to the presence of minute concentrations of impurity atoms
4 Ceramic compounds indicated by a combination of metallic elements with nonmetallic elements POLYMERS ¾Electrical insulation ¾Thermal insulation ¾Chemical resistance ¾Magnetic inertness ¾Extremely light weight ¾Toughness ¾Transparency ¾Colorability The elements associated with commercial polymers COMPOSITES A composite material is a combination of two or more chemically different materials, having a distinct interface between them, which act together to produce a desired (tailored) set of properties. A composite is designed to combine the best characteristic of each constituent material. EXAMPLES OF COMPOSITES SEMICONDUCTORS Semiconductors have electrical properties that are intermediate between the electrical conductors and insulators. Furthermore, the electrical characteristics of these materials are extremely sensitive to the presence of minute concentrations of impurity atoms
The elements involved in semiconductors BIOMATERIALS Biomaterials are employed in components implanted into the human body for replacement of diseased or damaged body EEENERRHINHERE ADVANCED MATERIALS Examples of High-tech Lasers, integrated circuits, magnetic information Materials that are utilized technology applications are sometimes ptics, spacecraft, aircraft, and military rocketry termed advanced materials. and the thermal protection system for the space Nanostructured Materials Nanopaticles The building blocks of these materials, be it Scale metal, ceramic or polymers, are nanometer size building 目eibs tocks The properties of materials can be engineered by these building bl the 1-100 nm size range and their assembly Naotubes
5 The elements involved in semiconductors Biomaterials arc employed in components implanted into the human body for replacement of diseased or damaged body parts. BIOMATERIALS ADVANCED MATERIALS Materials that are utilized in hightechnology applications are sometimes termed advanced materials. Lasers, integrated circuits, magnetic information storage, liquid crystal displays (LCDs), fiber optics, spacecraft, aircraft, and military rocketry and the thermal protection system for the space shuttle orbiter. Examples of High-tech The properties of materials can be engineered by controlling the sizes of these building blocks in the 1-100 nm size range and their assembly. Nanostructured Materials The building blocks of these materials, be it metal, ceramic or polymers, are nanometer size particles
Nanoparticles Nano layers Nanotubes Application Areas X露 Manmfarturte 阻害S 材料性质 材料导论 材料性质 第二章材料的性质
6 材料导论 第二章 材料的性质 材料性质 阻燃性 晶相结构 相结构 微观结构 耐腐蚀性 组成 化学性质 颜色 光学性质 磁学性质 电学性质 热学性质 熔点 物理性质 动态力学性质 硬度 蠕变性质 韧性 压缩性质 拉伸性质 力学性质 材料性质 阻燃性 晶相结构 相结构 微观结构 耐腐蚀性 组成 化学性质 颜色 光学性质 磁学性质 电学性质 热学性质 熔点 物理性质 动态力学性质 硬度 蠕变性质 韧性 压缩性质 拉伸性质 力学性质 材料性质 阻燃性 晶相结构 相结构 微观结构 耐腐蚀性 组成 化学性质 颜色 光学性质 磁学性质 电学性质 热学性质 熔点 物理性质 动态力学性质 硬度 蠕变性质 韧性 压缩性质 拉伸性质 力学性质 材料性质
测试拉伸性质的样品 21力学性质 211拉伸性质 [届服点 极限强度断裂点 典型高分子材料的 应力一应变曲线 弹性区 (c AE=弹性模量 Extension 应变(em/m 偏屈服强度的确定 A:低碳钢;B:中碳钢;C:熟石膏;D:碳化悔 E:灰钟铁(压缩);F:灰钟铁(拉伸) 0c02
7 2.1力学性质 2.1.1 拉伸性质 测试拉伸性质的样品 屈服点 极限强度 断裂点 弹性区 塑性区 典型高分子材料的 应力－应变曲线 A：低碳钢；B：中碳钢；C：熟石膏；D：碳化钨； E：灰铸铁（压缩）；F：灰铸铁（拉伸） 偏 屈 服 强 度 的 确 定
材料的延展性 工程应力 工程应变:E= 断裂伸长率 100 截面积收缩率=A 真应力:G 100 真应变 度力-应变由 程真 例2-1设计一铝棒以承受200kN(0.2MN)的力 为确保安全,棒上最大应力不能超过170MPae 程应力-应变曲 力力 棒的长度至少为3.8m,受力时弹性形变不能超过 6mm。所用铝材的弹性模量为69GPa 变变 解:先利用工程应力的定义计算棒的截面积: 曲曲 0.2MN =1.18×10-3m2=1180mm g 170MN/m 但规定的最小长度为3.8m。加长棒的长度,截面 截面积可以为任何形状,为方便加工,设计 积必须随之变大。38m长的棒的最小应变为 圆棒,其直径为d A/ 6 =0.00158 ard2 1180m 即d=38.8mm 4 这一应变相应于110MPa的应力,小于最大应力 170MPa。则最小截面积为 最大容许弹性形变为6mm,而170MPa应力所对 应的应变约为0.0025,由工程应变的定义可确定 F 02MN 棒的最大长度 110Mm3=1.82×103m2=1820mm 01=7=0.0025即1=2400mm=24m 所以,为同时满足最大应力最小伸长两项条件, 棒的截面积至少为1820mm2,即直径至少48mm
8 断裂伸长率＝ 截面积收缩率＝ 100 0 0 × − l l l f 100 0 0 × − A A Af 材料的延展性 工程应力： 工程应变： 真应力： 真应变： A0 F σ = 0 0 l l − l ε = A F σ t = ∫ = = A A l l l dl 0 0 ln ln 真 应 力 应 变 曲 线 与 工 程 应 力 应 变 曲 线 对 比 例2－1设计一铝棒以承受200kN (0.2MN)的力。 为确保安全，棒上最大应力不能超过170MPa。 棒的长度至少为3.8m，受力时弹性形变不能超过 6mm。所用铝材的弹性模量为69GPa。 3 2 2 0 2 1.18 10 1180 170 / 0.2 m mm MN m F MN A = = = × = − σ 解：先利用工程应力的定义计算棒的截面积： 截面积可以为任何形状,为方便加工，设计一 圆棒，其直径为d: 最大容许弹性形变为6mm，而170MPa应力所对 应的应变约为0.0025，由工程应变的定义可确定 棒的最大长度： mm d mm d A 1180 38.8 4 2 2 0 = = 即 = π l mm m l l l l l l 0.0025 2400 2.4 6 0 0 0 0 0 = = = = ∆ = − ε = 即 所以，为同时满足最大应力最小伸长两项条件， 棒的截面积至少为1820mm2，即直径至少48mm。 但规定的最小长度为3.8m。加长棒的长度，截面 积必须随之变大。3.8m长的棒的最小应变为： 这一应变相应于110MPa的应力，小于最大应力 170MPa。则最小截面积为： 0.00158 3800 6 0 = = ∆ = l l ε 3 2 2 0 2 1.82 10 1820 110 / 0.2 m mm MN m F MN A = = = × = − σ
剪切强度 21力学性质 双双戏交W》 212剪切强度与挠曲强度 剪切力F作用下 剪应力:r=剪切应变:y=h 剪切模量:G=τ/ 弯曲强度 3FL 挠曲强度= 2wh 挠曲模量≈DF 4whδ 例22:一玻璃纤维增强复合材料的挠曲强度为35MPa, 解:将样品尺寸代入挠曲强度公式 挑曲模量为12GPa 315=3F=35×125 200mm,置于相距125mm两圆之间。计算使样品断裂 2h22×12×950.173F 所播的力以及样品断裘时的挠曲。假设无塑性形变。 0173=1819N 又由挠曲模量公式 124×10 LF1252×1819 4wh64×12×9.56
9 2.1力学性质 2.1.2 剪切强度与挠曲强度 剪切强度 剪应力： A0 F τ = 剪切应变： h δ s γ = 剪切模量：G=τ/γ 弯曲强度 2 2 3 wh FL 挠曲强度 ＝ 挠曲模量 ＝ δ 3 3 4wh L F 例2-2：一玻璃纤维增强复合材料的挠曲强度为315MPa， 挠曲模量为124GPa。一样品宽12mm，厚9.5mm ，长 200mm，置于相距125mm两圆辊之间。计算使样品断裂 所需的力以及样品断裂时的挠曲。假设无塑性形变。 解：将样品尺寸代入挠曲强度公式： F N F F wh FL 1819 0.173 315 0.173 2 12 9.5 3 125 2 3 315 2 2 = = = × × × = = 又由挠曲模量公式： mm wh L F 0.7 4 12 9.5 125 1819 4 124 10 3 3 3 2 3 = × × × × = = δ δ δ
用应力一应变曲线表征韧性 21力学性质 断裂点 213韧性 录表 材料的脆一韧转变 冲击强度 转温度 合型降袋一1 Ch式 交变应力 21力学性质 214疲劳强度
10 2.1力学性质 2.1.3 韧性 用应力－应变曲线表征韧性 冲 击 强 度 材料的脆－韧转变 2.1力学性质 2.1.4 疲劳强度 交变应力
