数字化实验系统的扩展与连接设计

随着我国计算机网络和IT行业以及数字化行业的发展和我国课程改革的需求,数字化实验系统已经有了一定的应用和发展。数字化实验系统的扩展和连接设计关于教育行业和IT行业。相比之下,我们做教育更关心的是科技让实验实现的过程而非结果。另外,我们研究数字化实验系统的目的是为了让学生更多的提高参与实验的兴趣并从中学到知识。所以,我们的数字化实验系统的扩展更多的应该是从学生的角度出发。     

Rare earth ceramic cutting tool and its cutting behavior when machining hardened steel and cast iron

The addition of rare earth element yttrium played an important role in the improvement of both mechanical properties and wear resistance of Al2O3/(W,Ti)C ceramic cutting tool material.Mechanical properties especially the fracture toughness and flexural strength were obviously increased when a suitable amount of the yttrium were added.Wear resistance of the developed rare earth ceramic cutting tool material was higher than that of the corresponding materials without rare earth in the machining of the hardened 45# carbon steel and cast iron HT20-40.Wear modes of the Al2O3/(W,Ti)C rare earth ceramic tool materials were mainly flank wear and crater wear accompanied with slight notch wear when machining the hardened carbon steel.Wear mechanisms were major abrasive wear at low cutting speed and adhesive wear at high cutting speed.Wear modes were nearly the same except that the adhesion phenomenon in the crater area was intensified when machining cast iron.The flank wear area was relatively smooth with no obvious plowing phenomenon which was possibly concerned with the workpiece of low hardness and the adhesion phenomenon at high cutting temperature.     

多元梯度自润滑陶瓷刀具材料的研制

针对均质自润滑陶瓷刀具材料不能合理兼顾减摩性能及耐磨性能的难题,运用功能梯度材料的设计思想研制出一种梯度自润滑陶瓷刀具材料。这种新型自润滑刀具材料的特征是固体润滑剂由其表层向内层梯度减少,并且材料表层存在残余压应力。提出多元梯度材料的组成分布模型,按该模型得出的组分梯度设计结果,采用粉末叠层铺填与真空热压烧结工艺制备Al2O3/TiC/CaF2梯度自润滑陶瓷刀具材料。该梯度自润滑陶瓷刀具材料的显微结构呈现出与组成分布一致的梯度变化,表层形成了残余压应力,其抗弯强度、硬度和断裂韧度分别比相应的均质材料提高了21%、16%和5.9%。材料强度的提高主要是由于CaF2由表层到中间层梯度减少,硬度和断裂韧度的提高归因于材料表层的残余压应力。以Al2O3/TiC/CaF2梯度自润滑陶瓷刀具和相应的均质自润滑陶瓷刀具对45钢进行干切削试验,结果表明,梯度刀具的耐磨性能优于均质刀具。     

基于PIC单片机的通用胎压监测系统的设计

介绍了基于PIC单片机的轮胎压力通用监测系统的硬件组成及软件设计方法,阐述了基于英飞凌SP12传感器和带ASK/FSK调制发射芯片的rfPIC12F675F微控制器的轮胎监测模块设计方案和基于PIC16F877A单片机的中央主机接收模块的设计方案,并给出了模块硬件电路以及相关程序框图、通信协议和算法等;该系统可随时测定每个轮胎内部的实际温度、瞬压、加速度和传感器电压,确定故障轮胎并实时发出警告,有效避免事故的发生;该方案的提出对国内TPMS产品的普及和功能优化有着重要意义.     

纳米CaF2对自润滑陶瓷材料力学性能的影响

采用真空热压烧结工艺制备一种添加纳米固体润滑剂CaF2的新型自润滑陶瓷材料,其力学性能显著高于添加微米CaF2的自润滑陶瓷材料,并且断裂韧性高于不含CaF2的复合陶瓷材料。结果表明:烧结后纳米CaF2主要位于基体晶粒内部,形成晶内型纳米结构。相比于添加微米CaF2,添加纳米CaF2时复合陶瓷材料的弹性模量增加了34%,这是材料硬度改善的主要原因。纳米CaF2诱发的穿晶断裂有助于提高复合陶瓷材料的断裂韧性和抗弯强度,裂纹偏转是添加纳米CaF2的复合陶瓷材料的主要增韧机制。