AT90CAN128在船舶气象仪显示控制单元的应用

主要介绍了低功耗的8位AVR单片机AT90CAN128的工作原理及其在船舶气象仪显示控制单元中的应用。经实践证明,单片机AT90CAN128在船舶气象仪显示控制单元应用中,硬件电路设计大大简化,提高通信效率和安全性,增强系统的可靠性。     

C-276合金冷金属过渡焊接焊缝熔敷金属耐蚀性研究

摘要：C-276合金在氧化性和非氧化性酸中都具有很好的耐腐蚀性,所以在精对苯二甲酸（PTA）装置中应用较多。在化工容器设计时,虽然没有明确规定哪些场合使用复合板或堆焊,但是,考虑到堆焊层是铸造枝晶状奥氏体组织,复合板是轧制孪晶奥氏体组织,而且堆焊的热过程比复合的热过程复杂。以C-276钢板为参考,研究了c-276合金冷金属过渡（CMT）焊接焊缝熔敷金属的耐蚀性,供盯A装置制造厂参考。     

CMT电弧增材制造Cu-Ni-Al-Mn-Fe铝青铜合金微观组织性能研究

目的研究冷金属过渡技术(Cold metal transfer,简称CMT)增材制造Cu-Ni-Al-Mn-Fe铝青铜合金的微观组织成形规律。方法采用CMT电弧增材的方式制备了Cu-Ni-Al-Mn-Fe铝青铜合金的薄壁试样件,研究了试样件在不同位置、不同方向的微观组织。结果 CMT电弧增材制造Cu-Ni-Al-Mn-Fe铝青铜合金的微观组织分为3个区域,前3层的不稳定区域主要是由基材树枝晶到柱状晶的转变区域;第3层到最后一层的稳定区域主要是外延生长的柱状晶区;在最后一层靠近空气侧约360μm厚度范围内,出现转向枝晶。交替往复电弧增材的Cu-Ni-Al-Mn-Fe铝青铜合金,在每层顶部均会形成转向枝晶,但随后新一层电弧增材的熔池会熔化顶部形成的转向枝晶,最终在微观组织形貌上表现出柱状晶外延生长的形式。结论通过控制合适工艺参数,可以获得致密无缺陷的CMT电弧增材制造Cu-Ni-Al-Mn-Fe铝青铜合金薄壁试样,在试样的稳定区域,微观组织是外延生长的柱状晶,柱状晶的晶界上Al,Ni,Mn元素产生富集现象,质量分数高于平均值。在柱状晶的晶内,Cu元素高于均值,而Al,Ni,Mn元素质量分数均低于均值,这与柱状晶的形核顺序有关。     

超声功率对7075铝合金CMT焊接接头的组织与性能的影响

为了解决铝合金接头的气孔多、晶粒粗大、力学性能差等问题,使用冷金属熔滴过渡(CMT)焊接方法完成对7075铝合金薄板的焊接,在焊接过程中引入超声波。通过金相、EBSD、力学性能等测试考察了不同超声功率对焊接接头气孔、微观结构和力学性能的影响。结果表明,超声振动可以显著地减小气孔数量、增加熔宽,并且其焊接热影响区（HAZ）的宽度随超声功率的增加而减小;超声功率为1200 W时焊接接头显微硬度较无超声提高87.514 MPa,抗拉强度提高85 MPa,断后伸长率提高1.4%。由EBSD结果分析可知,当超声功率为1200 W时焊缝平均晶粒尺寸36.89μm,比未施加超声时减小了9.99μm,焊缝晶粒得到了明显细化;随着超声功率的增加提高了晶粒的大角度晶界的比例,焊接接头的塑性有所增加。     

CMT电弧增材制造316L不锈钢成形精度与组织性能分析

针对电弧增材制造成形问题,提出基于三维表面粗糙度参数的零件表面质量评价方法. 以高氮钢为例,采用CMT工艺进行多道搭接试验,通过三维扫描设备提取零件表面信息,计算表面轮廓均方根偏差S_q和轮廓偏斜度S_sk,对比计算所得数据与实际表面成形情况,并利用所提出的方法研究了增材制造过程中电弧摆宽对多道搭接表面质量的影响. 结果表明,此评价方法所得数据规律与实际成形情况基本吻合,具有较好的适应性和科学性. 根据数值S_q和S_sk大小可将成形表面质量由优到差分为A,B,C,D 4个等级. 电弧增材制造的热输入和电弧摆宽对成形表面质量影响较大. 在热输入较大时,电弧摆宽为15和10 mm时,熔敷焊道余高小、宽高比大,搭接成形更好.     

交流CMT焊接工艺对2198铝锂合金接头组织及性能的影响

铝锂合金是航空航天设备减重的理想轻质高强材料。采用交流CMT工艺并填充ER4043焊丝焊接厚2 mm的2198-T8铝锂合金薄板,并采用金相显微镜、维氏显微硬度计和拉伸试验机研究交流CMT对2198铝锂合金接头气孔、显微组织、力学性能的影响。结果表明,焊接电流90 A、电压10.7 V、焊接速度80 cm/min时,焊缝成形良好,焊接接头无宏观裂纹缺陷;利用显微镜可观察到焊接接头存在较多的气孔;熔合线显微硬度最低为68 HV;接头最大抗拉强度270 MPa,达到母材的64.3%,断裂方式为准解理断裂。     

Characterisation of the cold metal transfer (CMT) process and its application for low dilution cladding

The process characteristics of the synergic cold metal transfer (CMT) process have been examined for welding aluminium alloy. Utilising a simple backlighting system and through the arc monitoring the droplet transfer modes were identified. Whilst the modified short circuit mode was evident for the lower parameter range, a two part transfer mode based upon a combination of spray and short circuit transfer was observed for the mid to upper parameter range. The technology was also explored as a cladding process for applying to ternary alloyed (Al-Cu-Mg) aluminium plate. This alloy system is known to be susceptible to solidification cracking when MIG welded using the binary Al-2319 (Al-Cu) filler wire, this being due to the wide element freezing range of the weld resulting from mixing with the base material. Utilising this filler, weld dilution ratios for both CMT and pulsed welding were identified across the examined parameter range. The CMT process exhibited greater control of dilution that enabled deposition of a quasi-binary (Al-Cu) layer exhibiting a less crack susceptible composition. Onto this layer conventional MIG welding could be applied which could potentially eradicate cracking using a binary filler wire.     

A modified model of computational mass transfer for distillation column

The computational mass transfer (CMT) model is composed of the basic differential mass transfer equation, closing with auxiliary equations, and the appropriate accompanying CFD formulation. In the present modified CMT model, the closing auxiliary equations [Liu, B.T., 2003. Study of a new mass transfer model of CFD and its application on distillation tray. Ph.D. Dissertation, Tianjin University, Tianjin, China; Sun, Z.M., Liu, B.T., Yuan, X.G., Liu, C.J., Yu, K.T., 2005. New turbulent model for computational mass transfer and its application to a commercial-scale distillation column. Industrial and Engineering Chemistry Research 44, 4427-4434] are further simplified for reducing the complication of computation. At the same time, the CFD formulation is also improved for better velocity field prediction. By this complex model, the turbulent mass transfer diffusivity, the three-dimensional velocity/concentration profiles and the efficiency of mass transfer equipment can be predicted simultaneously. To demonstrate the feasibility of the proposed simplified CMT model, simulation was made for distillation column, and the simulated results are compared with the experimental data taken from literatures. The predicted distribution of liquid velocity on a tray and the average mass transfer diffusivity are in reasonable agreement with the reported experimental measurement [Solari, R.B., Bell, R.L., 1986. Fluid flow patterns and velocity distribution on commercial-scale sieve trays. AI.Ch.E. Journal 32, 640-649; Cai, T.J., Chen, G.X., 2004. Liquid back-mixing on distillation trays. Industrial and Engineering Chemistry Research 43, 2590-2597]. In applying the modified model to a commercial scale distillation tray column, the predictions of the concentration at the outlet of each tray and the tray efficiency are satisfactorily confirmed by the published experimental data [Sakata, M., Yanagi, T., 1979. Performance of a commercial scale sieve tray. Institution of Chemical Engineers Symposium Series, vol. 56, pp. 3.2/21-3.2/34]. Furthermore, the validity of the present model is also shown by checking the computed results with a reported pilot-scale tray column [Garcia, J.A., Fair, J.R., 2000. A fundamental model for the prediction of distillation sieve tray efficiency. 1. Database development. Industrial and Engineering Chemistry Research 39, 1809-1817] in the bottom concentration and the overall tray efficiency under different operating conditions. The modified CMT model is expected to be useful in the design and analysis of distillation column.     

Research on CMT welding of nickel-based alloy with stainless steel

Cold Metal Transfer （CMT） welding technique is a new welding technique introduced by Fronins company. CMT welding of nickel-based alloy with stainless steel was carried out using CuSi3 filler wire in this paper. Effects of welding parameters, including welding current, welding speed, etc, on weld surface appearance were tested. Microstructure and mechanical properties of CMT weld were studied. The results shaw that the thickness of interface reaction layer of the nickel- based alloy is 14. 3 μm, which is only 4. 33% of base material. The weld is made up of two phases, α-copper and iron-based solid solution. Rupture occurs initially at the welded seam near the edge of stainless steel in shear test. The maximum shear strength of the CuSi3 welded joint is 184. 9 MPa.