CVD金刚石厚膜刀具耐磨性的试验

本文简要介绍了ＣＶＤ金刚石刀具的特点，重点进行了ＣＶＤ金刚石厚膜刀具与国内外ＰＣＲ刀具的耐磨性对比试验。结果表明，ＣＶＤ金刚石刀具有优异的耐磨性，但韧性略低。     

CVD金刚石涂层刀具切削性能与磨损机理研究

针对普通刀具切削质量差、刀具耐用度低等问题,对CVD涂层刀具制备方法及切削性能进行研究。首先以硬质合金刀具为基体通过CVD方法制备金刚石涂层,分析涂层表面形貌。然后在不同条件下进行铝合金材料的干式切削试验,分析金刚石涂层对切削力、切削温度以及工件表面粗糙度的影响规律。最后,通过对刀具磨损机理的分析,讨论涂层对刀具使用寿命的影响。研究结果表明,所制备的涂层刀具能够降低切削力和切削温度,大大提高刀具的切削性能和工件的表面质量,并能有效提高刀具使用寿命。     

纳米金刚石涂层刀具高速铣削7075铝合金的工艺参数优化

采用热丝CVD法制备纳米金刚石薄膜涂层刀具,利用场发射扫描电子显微镜表征薄膜的表面形貌,并用已制备的CVD金刚石涂层刀具,在无润滑干切条件下高速铣削7075铝合金工件,对其精铣工艺参数进行单因素及正交试验,探索精铣后工件的表面粗糙度变化规律并进行工艺参数优化。结果表明:随着主轴转速n从5000 r/min提高到8000 r/min, 工件平均表面粗糙度在逐级缓慢降低;当进给速度v_f在1000～7000 mm/min范围内,随着v_f提高工件平均表面粗糙度快速增大,在v_f为7000 mm/min时,其值达1.790 μm;当轴向切削深度a_p在0.1～0.4 mm范围内,随着a_p提高,工件平均表面粗糙度逐步增大,但a_p在0.2 mm之后其增大趋势变缓。对7075铝合金工件精铣表面粗糙度影响最大的是v_f,其次为n,a_p的影响最弱;其精铣的最优参数组合是a_p=0.2 mm、v_f=1 000 mm/min、n=8 000 r/min,精铣后的表面粗糙度平均值为0.516 μm。选用纳米金刚石薄膜涂层刀具精铣7075铝合金时,为得到较低的表面粗糙度,应选择高主轴转速、低进给速度、合适的轴向切削深度。      

CVD金刚石厚膜刀具的研究进展与应用现状

金刚石厚膜片是采用化学气相沉积的方法制备出来的一种全晶质多晶纯金刚石材料,其物理性能和天然金刚石非常接近,而化学性质则完全相同。本文对CVD金刚石厚膜刀具的研究进展、制备方法、性能特点、切削试验结果及应用前景进行了简要的综述。     

金刚石刀具及切削有机复合材料磨损状况的研究

本文主要介绍了天然单晶金刚石、聚晶金刚石(PCD)及金刚石膜(CVD)的特性,分别进行了几种PCD、CVD切削有机复合材料的试验,重点分析了其刀具的耐磨性。     

铝合金高速切削刀具磨损研究进展

由于铝合金高速切削过程中切削温度高,导致刀具严重磨损,降低了刀具寿命和零件加工精度,因此准确预测刀具磨损和分析刀具磨损规律至关重要。分别从刀具寿命模型和刀具磨损速率模型概述刀具磨损理论模型研究进展,基于切削用量、刀具性质和冷却方式分析刀具磨损规律。从已有研究来看,在铝合金高速切削过程中刀具磨损随切削速度和进给量增大而增大,切削深度无明显规律;常见刀具磨损有黏结磨损、磨粒磨损和扩散磨损,其中黏结磨损为主要刀具磨损机制。     

CVD金刚石薄膜涂层刀具切削性能研究

本文采用不同涂层工艺的ＣＶＤ金刚石薄膜刀具切削高硅铝合金,观测比较刀具的磨损过程、磨损与破损形貌及工件表面粗糙度,分析ＣＶＤ金刚石薄膜刀具切削主崖裂口合金的磨损机理和失效原因。研究结果可为涂层工艺的提供了理论依据。     

聚晶金刚石刀具磨损研究综述

研究刀具的磨损机理及磨损规律，对于改善切削加工的工艺参数，提高刀具的耐用度和加工生产率，研制新型的刀具材料以及合理地选择刀具材料，提高被加工工件的表面质量，具有一定的理论与实际意义，本文在国内外关于聚晶金刚石刀具磨损机理研究的基础上，详细阐述了聚晶金刚石刀具的磨损形态，磨损成因以及磨损规律，同时提出了该研究领域目前仍然存在急待解决的问题。     

Computer-aided cooling curve analysis of A356 aluminum alloy

Computer aided cooling curve analysis (CA-CCA) is very useful in the foundry industry for easy and fast evaluation of a variety of properties. Typical applications include the prediction of the temperatures and amounts of different phases appearing during solidification and monitoring of the quality of melt in terms of Si- modification, grain refinement, inoculation, and graphite spheoridization. The use of cooling curve analysis can be extended to many other areas of solidification also, assuming the calculated values are reasonably accurate. The calculation of zero curve, which is vital in cooling curve analysis, offers many problems however. In this study, an attempt was made to investigate the problems of zero curve calculation and a new method is suggested to minimize calculation errors. An in-house developed computer program was used for a complete analysis of aluminum alloy A356 to determine the latent heat and solid fraction values.     

A356铝合金微弧氧化膜微动磨损行为的研究

采用微弧氧化（MAO）在A356铝合金表面制备MAO膜,利用球-平面接触在SRV-V微动摩擦磨损机上探究变载荷和位移下微弧氧化对A356微动磨损机理的影响。结果表明：MAO膜由疏松层和致密层构成,其均匀性、致密性和结合力良好。MAO膜的摩擦系数、磨损率均低于A356,MAO膜减摩耐磨性较好。随位移增加MAO膜的摩擦耗散能系数低于A356,MAO膜能提升A356微动磨损过程的稳定性。载荷增加时A356磨损机制为磨粒磨损-粘着磨损,伴随犁削和疲劳剥层; MAO膜磨损机制为磨粒磨损-粘着磨损和疲劳剥落。位移增加时A356磨损机制为粘着磨损和疲劳剥落,伴随微犁削;MAO膜磨损机制为粘着磨损和疲劳剥层-粘着磨损和磨粒磨损。A356的磨痕内聚集Fe、O元素,存在材料转移和氧化磨损;MAO膜磨痕内聚集Fe元素,存在材料转移。     

A356合金流动性测试研究

对A356合金流动性能进行测试.结果表明,下列条件测试结果较佳:采用复沟型金属流动测试仪;涂料涂刷厚度0.5mm～0.8mm,两次涂刷;熔体在720℃保温,30min～40min;浇铸温度为690℃;模具保温温度为60℃～80℃.     

Thixoforming of AA 2017 aluminum alloy composites

A comparative evaluation has been carried out on the microstructure of aluminum based SiC and Al₂O₃ particle reinforced composites produced by semi-solid direct squeeze forming of composite powder at temperatures of 635-645 °C. The study is focused on the distribution of the reinforcement and the intermetallic phases, the porosity content, the microstructure of the matrix phase, the interfacial state and mechanical properties. The particle size of the reinforcements, the time of the high-energy ball milling procedure for the fabrication of composite powder and the semi-solid forming temperature had a strong influence on the quality of sample in terms of distribution of reinforcement and interfacial interaction. Ball milling improves the interface formation between reinforcement and matrix and influences the remelting behaviour. Increasing ball milling time and decreasing semi-solid forming temperature with isothermal holding time resulted in relatively homogenous microstructures and in a reduced amount of interaction between SiC and metal matrix. Best results were obtained for 5 vol.% SiC_p composites after 3 h ball milling, semi-solid formed at 635 °C and held for 10 min.     

Rheo-squeeze casting of semi-solid A356 aluminum alloy slurry

The effect of pouring temperature, electromagnetic stirring power and holding process on semi-solid A356 aluminum alloy slurry was investigated, then the slurry was squeeze-cast. The results show that when the pouring temperatures are properly above the liquidus line, for example 630-650 °C, the slurry with spherical primary α(Al) grains can be prepared under the stirring power of 1.27 kW. The slurry is then homogeneously held for a short time, and the primary α(Al) grains are further ripened and distributed evenly in the slurry. The results of the rheo-squeezed casting experiments show that the injection specific pressure has a great effect on the filling ability of the semi-solid A356 aluminum alloy slurry, and the higher the injection specific pressure is, the better the ability for the slurry to fill the mould cavity is. When the injection specific pressure is equal to or above 34 MPa, the whole and compact rheo-squeezed castings can be obtained. The microstructure of the castings indicates that the shape, size and numbers of the primary α(Al) grains in different parts of the castings are highly consistent. After being held at 535 °C for 5 h and then aged at 155 °C for 12 h, the ultimate strength of the rheo-squeezed castings can reach 300-320 MPa, the yield strength 230-255 MPa, and the elongation 11%-15%.     

多级热处理工艺对铝合金AA7049性能的影响(英文)

T6态高强7xxx系列铝合金对应力腐蚀开裂敏感。采用回归和再时效热处理(RRA)可以提高其抗应力腐蚀开裂性能而不降低其强度性能。研究了多级热处理工艺对7049铝合金性能和组织的影响。通过电导率测量、DSC分析和TEM组织观察,考察合金在不同热处理态的组织变化。DSC分析表明,RRA处理会导致合金的显微组织发生显著变化,RRA处理态合金的组织与T6和T73态合金的组织明显不同。RRA处理可以使合金保持在T6态的强度且获得T73态的热力学稳定性能。     

Development of roping in an aluminum automotive alloy AA6111

The roping behavior of an automotive sheet alloy AA6111 was investigated for two processing schedules that led to the production of: (1) roping and (2) non-roping materials. In contrast to the data available in the literature, this study shows that both ridges and valleys on the upper and lower surfaces are irregularly distributed in the rolling direction (RD) and that ribbed profiles and corrugations are rare. The electron back scattering diffraction (EBSD) experiments demonstrated that banded structures of Goss are more evident throughout the specimen thickness than similar bands of Cube texture. The volume texture of the hotband comprised of the strong brass–copper–S fiber, while exclusively Cube texture was present in the non-roping material. In addition to the Cube, the Goss, G1, S and [100]//RD fiber components were produced in specimens associated with roping. The present study shows that the spatial distribution of the Goss component is responsible for the roping behavior in aluminum alloy AA6111.     

Wear behaviors of pure aluminum and extruded aluminum alloy (AA2024-T4) under variable vertical loads and linear speeds

The aim of this study was to investigate the transition of wear behavior for pure aluminum and extruded aluminum alloy 2024-T4 (AA2024-T4). The wear test was carried using a ball-on-disc wear testing machine at various vertical loads and linear speeds. The transition of wear behaviors was analyzed based on the microstructure, wear tracks, wear cross-section, and wear debris. The critical wear rates for each material are occurred at lower linear speed for each vertical load. The transition of wear behavior was observed in which abrasion wears with the generation of an oxide layer, fracture of oxide layer, adhesion wear, severe adhesion wear, and the generation of seizure occurred in sequence. In case of the pure aluminum, the change of wear debris occurred in the order of blocky, flake, and needle-like debris. Cutting chip, flake-like, and coarse flake-like debris was occurred in sequence for the extruded AA2024-T4. The transition in the wear behavior of extruded AA2024-T4 occurred slower than in pure aluminum.     

CVD金刚石厚膜工具制作工艺和切削实验研究探讨

采用特殊的活性焊料对CVD膜与硬质合金基体进行真空焊接，获得了大于500MPa的剪切强度，此强度已经接近金刚石膜的剪切强度。针对不同工艺的CVD刀具与PCD刀具对切削力和被加工材料表面粗糙度进行了切削试验对比，在铜材和硅铝合金的切割实验中CVD刀具达到的表面粗糙度达到表面粗糙度1．3μm和0.9μm，远高于使用PCD刀具获得的表面粗糙度2．9μm和1．4μm；结果表明CVD刀具较PCD刀具有明显的优势。     

Wear of alloy tool steels under impact conditions

Conclusions The impact wear rate depends on the impact energy, ductility, hardness, and phase composition of steels.Tyumen' Industrial Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 77–78, January, 1973.