| 词或词组 | 中文 | 英文解释中文解释 |
|---|---|---|
| Nano machining | 纳米加工 |
The machining of silicon chips typically less than 1 nm thick. 硅芯片的加工通常小于1nm厚。 |
| Nanomanufacturing | 纳米制造 |
1. The manufacture of nanoscale materials. 2. The manufacture of components or devices that have critical dimensions of order 1 nm. 1.纳米材料的制造。2.具有1nm级临界尺寸的部件或装置的制造。 |
| Nanomaterial | 纳米材料 |
A material defined by the European Commission as ‘A natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1–100 nm. In specific cases and where warranted by concerns for the environment, health, safety or competitiveness the number size distribution threshold of 50% may be replaced by a threshold between 1 and 50%.’ 由欧盟委员会定义为“含有颗粒的天然、偶然或人造材料，处于未结合状态或聚集体或凝聚体，其中，对于数量-尺寸分布中的50%或更多颗粒，一个或多个外部尺寸在1-100nm的尺寸范围内”。在特定情况下，如果考虑到环境、健康、安全或竞争力，50%的数量大小分布阈值可以由1%到50%之间的阈值代替。 |
| Nanoparticles | 纳米颗粒 |
Particles with dimensions of order 1 nm which have either been introduced into microstructures for reinforcement or are present as impurities. 尺寸为1nm级的颗粒，其已被引入微结构中用于增强或作为杂质存在。 |
| Nanotechnology | 纳米技术 |
The science and engineering of materials that have been structured on length scales of 1–100 nm, resulting in modified physical properties owing to changes in the ratio of surface area to volume (atoms on surfaces having different symmetry from those in the bulk) and because many of the fundamental physical processes that underpin the properties of materials have a characteristic length scale of a few nm, so that alteration of microstructure at the nm level alters the bulk properties. 材料科学与工程，其结构长度为1-100nm，由于表面积与体积之比的变化（表面上的原子与体中的原子具有不同的对称性），并且支撑材料性质的许多基本物理过程具有几纳米的特征长度尺度，因此改变纳米级微观结构会改变体性质。 |
| Natural aging | 自然时效 |
Spontaneous aging of a supersaturated solid solution at room temperature. 过饱和固溶体在室温下的自发时效。 |
| Natural unit system (n.u. system) | 自然单位制（n.u.制） |
A non-SI system of units, based on fundamental constants, used in high-energy and particle physics. The n.u. of speed is the speed of light in a vacuum, c0 = 299 792 458 m/s. 基于基本常数的非国际单位制，用于高能和粒子物理n.u.速度是真空中的光速，c0=299792458m/s。 |
| Nautical mile (M) | 海里（M） |
A special unit of distance employed for marine and aerial navigation. The conversion to SI is 1 M = 1 852 m. 用于海上和空中导航的特殊距离单位。SI的转换为1M＝1852m。 |
| Net weight (Unit N) | 净重（单位：N） |
The difference between the gross weight of any container including its contents and the tare weight of the empty container. 任何容器（包括其内容物）的毛重与空容器皮重之间的差值。 |
| Neutralization number | 中和值 |
An ASTM number given to quenching oils that reflects the oil’s tendency towards oxidation and sludging. 淬火油的ASTM编号，反映了油的氧化和成泥趋势。 |
| Newton (N) | 牛顿（N） |
The basic unit of force in the SI system, defined as the force that results in an acceleration of 1 m/s² when acting on a 1 kg mass. SI国际单位制中力的基本单位，定义为作用于1kg质量时产生1m/s²加速度的力。 |
| Newton’s law of gravitation | 牛顿万有引力定律 |
(Newton’s law of universal gravitation) Any two bodies exert a gravitational force of attraction F on each other directed along the line joining their centres of mass, in magnitude proportional to the product of their masses and inversely proportional to the square of the distance r between them. （牛顿万有引力定律）任何两个物体沿其质心连接线相互施加引力F，其大小与其质量乘积成正比，与它们之间距离r的平方成反比。 |
| Newton’s law of viscosity | 牛顿内摩擦定律 |
The shear stress between two parallel layers of fluid is proportional to the velocity of one relative to that of the other, and inversely proportional to the distance between them. The constant of proportionality is the dynamic viscosity μ. For a Newtonian fluid μ is independent of pressure gradient, shear stress, and strain, but may change with temperature and pressure. 两个平行流体层之间的剪切应力与其中一层相对于另一层的速度成正比，与它们之间的距离成反比。比例常数是动态粘度μ。对于牛顿流体，μ与压力梯度、剪切应力和应变无关，但可能随温度和压力而变化。 |
| Nipple | 喷嘴 |
A device containing a non-return valve screwed into a lubrication point through which grease may be introduced, for example into a bearing. 一种包含止回阀的装置，该止回阀拧入润滑点，通过该润滑点可以将润滑脂引入，例如轴承中。 |
| Noble metals | 贵金属 |
Metallic elements from periods (rows) 5 and 6 of the periodic table, namely ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold. They resist corrosion and oxidation and are used for electrical contacts, thin-film circuits, and electroplating. Gold, silver, and platinum used for jewellery are also known as precious metals. They have face-centred cubic crystal structure and good ductility. 周期表第5和第6周期（行）中的金属元素，即钌、铑、钯、银、锇、铱、铂和金。它们抗腐蚀和氧化，用于电触点、薄膜电路和电镀。用于珠宝的金、银和铂也被称为贵金属。它们具有面心立方晶体结构和良好的延展性。 |
| Nominal diameter | 公称直径 |
The ‘‘catalog diameter’’ of a fastener. Usually roughly equal to the diameter of the body, or the outer diameter of the threads. 紧固件的“目录直径”。通常大致等于主体的直径或螺纹的外径。 |
| Nominal power (Unit kW) | 公称功率（单位kW） |
1. For an internal combustion engine, the average power output of a typical production engine under normal working conditions measured according to SAE standard J 1349/ISO 1585. 2. For an electric motor, the rated equivalent mechanical power output. 1.对于内燃机，根据SAE标准J 1349/ISO 1585测量的正常工作条件下典型生产发动机的平均功率输出。2.对于电动机，额定等效机械功率输出。 |
| Nominal size | 公称尺寸 |
The intended size of a component. The actual size will depend on manufacturing tolerances. 组件的预期尺寸。实际尺寸取决于制造公差。 |
| Nominal stress | 名义应力 |
The stress at a point calculated on the net cross section by simple elasticity theory without taking into account the effect on the stress produced by stress raisers such as holes, grooves, fillets, etc. 通过简单弹性理论在净截面上计算的点处的应力，不考虑孔、槽、圆角等应力提升器产生的应力影响。 |
| Non-ferrous metal | 有色金属 |
Strictly, all metals and alloys that do not contain iron, but usually taken to mean aluminium- and copper-based alloys. 严格来说，所有不含铁的金属和合金，但通常指铝基和铜基合金。 |
| Nonlinear behavior | 非线性行为 |
A fastener or joint system is said to exhibit nonlinear behavior when the relationship between the External load on the joint and deformation of the parts is nonlinear, or when the relationship between increasing Preload and deformation is nonlinear. 当接头上的外部载荷与零件变形之间的关系是非线性的，或者当增加的预载荷与变形之间的联系是非线性的时，可以说紧固件或接头系统表现出非线性行为。 |
| Normal stress (Unit N) | 法向应力（单位：N） |
The stress component perpendicular to a plane on which forces act. Normal stress may be either tensile stress or compressive stress. A stress in a fluid (such as pressure) or a solid, that is perpendicular to the surface on which it acts. The surface may be a real external surface or an imaginary internal one. 垂直于受力平面的应力分量。法向应力可以是拉应力或压应力。流体（如压力）或固体中垂直于其作用表面的应力。该表面可以是真实的外表面或假想的内表面。 |
| Normal temperature and pressure (NTP) | 常温常压（NTP） |
Reference conditions defined by NIST as 20°C and 1 atm. NIST定义的参考条件为20°C和1atm。 |
| Normality | 常态 |
The principle that the vector sum of plastic strain increments is perpendicular to the yield surface. 塑性应变增量矢量和垂直于屈服面的原理。 |
| Normalizing | 正火 |
Heating a ferrous alloy to a suitable temperature above the transformation range and then cooling in air to a temperature substantially below the transformation range. 将铁合金加热至高于转变范围的合适温度，然后在空气中冷却至基本低于转变范围的温度。 |
| Notch brittleness | 缺口脆性 |
Susceptibility of a material to brittle fractureat points of stress concentration. For example, in a notch tensile test, the material is said to be notch brittle if the notch strengthis less than the tensile strength of an unnotched specimen. Otherwise, it is said to be notch ductile. 材料在应力集中点易发生脆性断裂。例如，在缺口拉伸试验中，如果缺口强度小于无缺口试样的抗拉强度，则称材料为缺口脆性材料。否则，称其为缺口韧性。 |
| Notch depth | 缺口深度 |
The distance from the surface of a notched test specimen to the bottom of the notch. In a cylindrical test specimen, the percentage of the original cross-sectional area removed by machining an annular groove. 从缺口试样表面到缺口底部的距离。在圆柱形试样中，通过加工环形槽去除的原始横截面积的百分比。 |
| Notch ductility | 缺口延展性 |
The percentage reduction in area after complete separation of the metal in a tensile test of a notched specimen. 在缺口试样的拉伸试验中，金属完全分离后的面积减少百分比。 |
| Notch strength | 缺口强度 |
The maximum load on a notched tensile-test specimen divided by the minimum cross-sectional area (the area at the root of the notch). Also known as notch tensile strength. 缺口拉伸试样上的最大载荷除以最小横截面积（缺口根部的面积）。也称为缺口抗拉强度。 |
| Nut | 螺母 |
A metal fastener of square, hexagon or other shape, having an internal thread which screws onto a bolt, stud or arbor. An internally-threaded fastener used with externally-threaded bolts. Usually hexagonal in shape but there is a multitude of other geometries, such as square, for special purposes and different gripping tools. 一种方形、六角形或其他形状的金属紧固件，具有内螺纹，可拧在螺栓、螺柱或心轴上。与外螺纹螺栓一起使用的内螺纹紧固件。通常为六边形，但也有许多其他几何形状，如方形，用于特殊用途和不同的夹持工具。 |
| Nut box mechanism | 螺母箱机械装置 |
In a lathe it is used to engage and disengage the lead screw for thread cutting. This comprises a pair of half-nuts capable of sliding in vertical slides in or out of mesh with the lead screw. 在车床中，它用于接合和分离丝杠以进行螺纹切削。这包括一对半螺母，能够在与丝杠啮合的垂直滑动中滑动。 |
| Nut factor | 螺母系数 |
An experimental constant used to evaluate or describe the ratio between the torque applied to a fastener and the Preload achieved as a result. 用于评估或描述施加在紧固件上的扭矩与由此获得的预载之间的比率的实验常数。 |
| Nut splitter | 螺母分离器 |
A tool for removing rusted-on and corroded nuts from bolts. It consists of a stiff steel ring that is placed around the nut. A screw thread passing through the ring bears diametrically on a wedged-shape tip that indents and cuts though a face of the nut. 从螺栓上去除锈蚀螺母的工具。它由一个围绕螺母放置的刚性钢环组成。穿过环的螺纹径向支撑在楔形尖端上，该尖端凹陷并穿过螺母的表面。 |
| Nut thickness | 螺母厚度 |
The nut thickness shall be the overall distance measured parallel to the axis of nut, from the top of the nut to the bearing surface, and shall include the thickness of the washer face where provided. 螺母厚度应为平行于螺母轴线测量的从螺母顶部到轴承表面的总距离，还应包括垫圈表面的厚度。 |