时间和温度对表面氧化法增强金刚石单晶抗压强度的影响

金刚石抗压强度是衡量人造金刚石机械性能的重要参数之一，本文以Griffith微裂纹理论为基础，认为对金刚石晶体颗粒进行表面氧化处理，使表面微裂纹钝化或消除，可以增强金刚石单晶颗粒强度和韧性，热力学计算表明，处理的温度越高，氧化反应进行的越彻底。但由于金刚石内部包裹体的存在，处理的时间和温度如果超过一定范围，就会对金刚石产生损伤，抗压强度或抗压强度提高值下降，本文选用熔融态的KNO3作为氧化剂，讨论在对金铡石单晶颗粒进行强化处理过程中时间与温度对抗压强度的影响，给出了金刚石表面氧化增强处理的温度和时间的适应区间；处理温度应控制在560℃～600℃之间，处理时间应在30min～60min之间。     

深冷处理金刚石颗粒的性能表征

对3种颗粒尺寸的人造金刚石进行深冷处理,并对处理前后的金刚石颗粒进行拉曼光谱、荧光光谱分析及静压强度测试。结果表明:粒度标记30/35的金刚石颗粒处理后静压强度平均值提高了23.2%,内部残余应力下降了25.93%。深冷处理使人造金刚石颗粒磁性降低,颗粒中的缺陷得到修复,内部残余应力释放,静压强度提高。      

真空微蒸发镀覆工艺参数对镀层质量及金刚石性能的影响

本文通过对金刚石镀Ti过程中镀层形成的演化过程的测试观察，研究了镀覆温度、时间等工艺参数的改变对镀层厚度控制及其随后的性能变化等。用扫描电镜观察了镀覆处理后金刚石的表面形貌，同时测定了镀覆处理后金刚石颗粒的静压强度和冲击韧性。结果表明，当镀覆温度高于100℃时镀层将由于厚度增加和应力过大，使其局部脱落，达到1100℃时脱落率达到60％；镀覆温度在900-1000℃范围内，对质量较好的金刚石静压强度和冲击强度达到最高，继续升高温度导致其强度数值下降；本文研究证明，对于石墨模具、含Fe40％的Cu—w基结合剂、1100℃／10min条件下热压烧结，镀覆温度为900—1000℃／60min保温所获得的Ti镀层具有最佳使用效果。     

双阴极等离子溅射沉积TiC薄膜对金刚石工具性能的影响*

采用双阴极等离子溅射沉积方法对金刚石颗粒表面进行镀TiC处理。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)进行形貌和物相分析。使用金刚石单颗粒静压强度测定仪和人造金刚石冲击强度测定仪检测金刚石的静压强度和冲击韧性。以相同型号和粒度的普通金刚石颗粒为对比样品,讨论了镀TiC处理对金刚石工具的影响。结果表明,金刚石表面形成了一层均匀且致密的TiC薄膜,该薄膜以柱状方式沿垂直于金刚石表面方向生长。在镀层的保护下,金刚石的单颗粒强度和冲击韧性得到了提高。由于镀层改善了金刚石对胎料的润湿性,金刚石工具的冲击强度和抗弯强度也得到了提高。     

金刚石的真空微蒸发镀技术

超硬磨料真空微蒸发镀覆技术是燕山大学完成的国家重点科技攻关项目，是一项国内外首创，处于国际领先水平的成果。尽管各种镀覆技术很多，除真空微蒸发镀覆技术外，还没有其它方法能够用于生产实际中。技术领先的标志是，真空微蒸发镀钛金刚石受热温度低至650℃，可在650～750℃之间任选，镀层与金刚石界面形成碳化物达到强力结合，结合强度大于140MPa；镀后单晶强度提高5％～20％；镀后增重随粒度不同在0．5％～3．0％。在工具烧结时，微蒸发镀钛层保护金刚石，工具中金刚石颗粒不脱落，出刃增高，工具寿命和效率大幅度提高。适用于各类金属结合剂金刚石工具。减少金刚石用量，降低生产成本。     

多切削刃金刚石颗粒烧结试验研究

为提高金刚石工具的锋利度和加工效率，延长其使用寿命，采用低温烧结的方法对金刚石颗粒表面进行多刃化处理。使用扫描电镜照片和质量损失率对不同烧结工艺的金刚石颗粒多刃化效果进行表征，并进行了碳化硅晶片研磨试验。结果表明:金刚石颗粒多刃化处理的最佳烧结工艺为:烧结温度750 ℃，烧结时间480 min，期间通10 kPa氧气2次，每次通气2 min，通气间隔2 h。在此条件下可获得大小适中，凹坑分布均匀的多刃化金刚石颗粒表面。碳化硅晶片研磨试验证明:多刃化金刚石颗粒与常规金刚石颗粒相比，材料去除率可提高1.1倍，研磨后晶片表面粗糙度R_a约为常规金刚石颗粒的24%，多刃化处理可显著提高金刚石颗粒研磨碳化硅晶片的抛光效率和精度。      

表面腐蚀对离心铸造铝基复合材料耐磨性的影响

采用离心铸造制备了Al-10Si-15Mg2Si复合材料.检测了该复合材料内层颗粒增强层在未经过腐蚀处理以及经过10％的NaOH溶液在常温下不同时间的腐蚀预处理后的耐磨性能.结果表明,复合材料增强层的磨损量随着腐蚀时间的延长呈现先降低后增加的变化趋势.讨论了腐蚀预处理对复合材料颗粒增强层耐磨性能的影响机制.     

对人造金刚石现行技术标准的认识与探讨

本文分析了目前国内人造金刚石技术标准的使用情况及其优缺点,现有技术标准为1997年发布的中华人民共和国机械行业标准《超硬磨料人造金刚石技术条件》,有关内容已难以满足企业控制产品质量的需要,因此有必要根据使用需要的发展不断更新和提高技术标准,提高其实用性。如提高粒度范围的标准、把粒度筛分和测定每克拉金刚石颗粒数二者结合作为粒度评定标准;增加静压强度测试取样量、改变静压强度计算方法及增加静压强度的强度分布特征;统一冲击韧性测试方法;增加金刚石晶体内部杂质及表面状态等指标,改善金刚石品级分类方法。     

人造金刚石单颗粒抗压强度测试仪对比分析

抗压强度是人造金刚石质量的重要指标，本文采用传统单颗粒抗压强度测定仪和Dia Test—SI型单颗粒抗压强度自动测定仪对金刚石标样进行检测对比分析．对同一样品不同时期多次测试和同一样品不同厂家测试，结果表明：传统单颗粒抗压强度测定仪测定的最大强度平均值和最小强度平均值相差15．38％和34％；而Dia Test—SI型单颗粒抗压强度自动测定仪的测定结果差值为4．1％、5．3％；证明DiaTest—SI型单颗粒抗压强度自动测定仪在测试中受操作水平及客观条件的影响较小，测试结果的稳定性比较好，各厂家测试结果的可比性强。     

热处理对金刚石颗粒表面钛包覆层组织与性能的影响

采用真空蒸发镀方法对金刚石颗粒表面进行镀钛处理,将镀钛金刚石分别在不同温度下进行真空热处理,用扫描电子显微镜、能谱仪和X射线衍射对金刚石颗粒的表面形貌、成分及其物相等进行分析,并采用金刚石单颗粒静压强度测定仪对其进行强度测试。结果表明:金刚石在880℃时开始碳化;钛包覆层只和碳化的金刚石发生界面反应,在880℃热处理温度下TiC先以点状形式析出,随着时间的延长,逐渐长大成雪花状,热处理温度为920℃时,镀层逐渐被氧化成TiO;TiC包覆层能够提高金刚石颗粒的热稳定性和静压强度,相对普通金刚石而言静压强度提高了14%。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.