CVD涂层硬质合金刀具的耐磨性和破损特性

通过系统的实验研究和理论分析，揭示了化学气相沉积（ＣＶＤ）涂层质合金刀具在磨损和破损状态下不同的失效特性和机理。，在耐磨性方面，重点分析了涂层的耐靡屏障作用，固体润滑作用和涂层与基体间的匹配作用，在破损特性方面，分析了表现残余应力与涂层剥落，脆性η相与界面裂纹，刃口钝化与塑性变形等内在规律。在此基础上又阐明了涂层质合金刀具对于切削条件的特殊适用性和选择性。     

Silicon surface treatment via CVD of inner steel tube surfaces

Inner surfaces of steel tubes should be protected against corrosion and oxidation by a coating in order to assure optimised application in power plants and the chemical industry. Since the silicon content in chromium alloyed steels improves the oxidation protection. Chemical vapour deposition (CVD) of Si has been investigated for martensitic 9% chromium steel (T91). The surface treatment was performed as a combined process of CVD at atmospheric pressure with heat treatment in a chemical atmosphere with high frequency heating (HF), automated with a Simatic PCS7. The Si out of SiCI₄ diffused into the steel lattice of the substrate surface. As a result, the Si‐content near the surface layer increased as a ferrite layer which did not transform to martensite during heat treatment. The excess of Si was converted to Si₃N₄ using NH₃. This improves the anti‐oxidation behaviour. The physical and chemical properties of the modified surfaces were investigated and characterised using the SEM, EDX, electron microprobe and X‐ray diffraction methods. The deformation capacity of a coated specimen was proven by means of hot tensile tests. It could be determined that in the ferritic layer Fe is substituted by Si with a maximum concentration of approx. 5%, however the Cr content was almost constant.     

Change Laws of Flake''''s Temperature during Making a Diamond Film by DC-PJ

Maldngdiamondfilmbydirectcurrentplasmajetisoneofhightechnologies.DevelopmenttrendofthetechnologyistOgetaIdleareafilmwithgoodqualitybyanequipmentwithhighpowerdirectcurrentplasmajetatPresent[l].However,duringthefilmgrowing,itsbasebodyhasvariabletempera...     

Cyclic and Isothermal Oxidation at 1,100 °C of a CVD Aluminised Directionally Solidified Ni Superalloy

CVD aluminide coatings deposited on a Directionally Solidified (DS) substrate were oxidized at 1,100 °C up to 240 h under isothermal and cyclic oxidation conditions to study the growth mechanisms of the oxide scales and the possible degradation of the coatings. The specimens were investigated using light and scanning electron (SEM) microscopy, energy-dispersive spectrometry (EDS) and X-Ray Diffraction (XRD). The results indicate that the coatings provide a much greater beneficial effect under isothermal conditions than upon cycling. The cycled specimens undergo oxide-scale spallation and increased roughening, which can derive from growth and thermal stresses as well as from the NiAl → Ni₃Al phase transformation associated with Al depletion. Under isothermal conditions, typical oxide scales formed with the appearance of some rumples. However, the origin of rumpling is uncertain from these experimental results.     

Al诱导a-Si:H薄膜的晶化

采用等离子体化学气相沉积方法在镀Al玻璃及单晶Si衬底上制备了氢化非晶硅(a-Si:H)薄膜,研究了样品在不同的热处理过程中Al对其晶化过程的影响.X射线衍射测量发现,由于Al的存在使a-Si:H的晶化温度大幅度降低,并得到了有强烈(111)结晶取向的多晶Si薄膜.X射线光电子能谱分析表明,热处理过程中Al向Si薄膜表面的扩散降低了Si的成核温度.     

碳纤维复合材料专用CVD金刚石涂层刀具的制备及试验研究

碳纤维增强复合材料(简称碳纤维复合材料)是以石墨纤维或碳纤维为增强材料的复合材料,具有耐磨性好、耐高温、强度高、密度小、比刚度高和低温性能好等优点,但在钻削过程中易使普通的硬质合金刀具磨损。而金刚石涂层刀具在钻削较硬金属材料和非金属材料时,具有良好的切削加工性。通过CVD金刚石刀具与普通的硬质合金刀具对碳纤维复合材料的钻削试验对比以及两种刀具的磨损研究可以得出,CVD金刚石涂层刀具的钻削性能明显好于普通的硬质合金刀具。     

Effects of Growth Parameters on the Morphology of CNTs/Cu Composite Powder Prepared Using Cr/Cu Catalyst by Chemical Vapor Deposition

采用化学共沉淀法制备了Cr/Cu复合粉体催化剂,并用化学气象沉淀法（CVD）原位合成CNTs/Cu复合粉末。利用SEM, TEM和Raman光谱分别对其微观形貌和结构进行表征。结果表明：采用化学气相沉淀法,使用10 wt%Cr/Cu 的催化剂,在混合气体(Ar/H2/C2H4) 流量2450/300 mL/min下,于1073 K 温度生长30 min,可以得到优质、结晶良好的 CNTs/Cu 复合粉末     

镁合金表面沉积铜钨复合涂层工艺及涂层性能研究

目的提高镁合金表面的耐蚀耐磨性。方法采用冷喷涂与化学气相沉积(CVD)相结合的方法在镁合金表面制备出Cu/W复合涂层,并对复合涂层的结构、成分、组织形貌、耐磨性、耐蚀性、结合力进行分析。结果镁合金基体沉积Cu/W复合涂层后,表面硬度提高了687.1HV,磨损率从0.032%降到0.020%,腐蚀电位正移了1.3 V,临界载荷相比直接化学气相沉积W涂层提高了120.5 N。结论Cu/W复合涂层显著提高了镁基体的耐磨、耐蚀性,涂层与基体结合力较高。     

Is the association between temperature and mortality modified by age, gender and socio-economic status?

Background

A number of studies have examined the relationship between high ambient temperature and mortality. Recently, concern has arisen about whether this relationship is modified by socio-demographic factors. However, data for this type of study is relatively scarce in subtropical/tropical regions where people are well accustomed to warm temperatures.

Objective

To investigate whether the relationship between daily mean temperature and daily all-cause mortality is modified by age, gender and socio-economic status (SES) in Brisbane, Australia.

Methods

We obtained daily mean temperature and all-cause mortality data for Brisbane, Australia during 1996-2004. A generalised additive model was fitted to assess the percentage increase in all deaths with every one degree increment above the threshold temperature. Different age, gender and SES groups were included in the model as categorical variables and their modification effects were estimated separately.

Results

A total of 53,316 non-external deaths were included during the study period. There was a clear increasing trend in the harmful effect of high temperature on mortality with age. The effect estimate among women was more than 20 times that among men. We did not find an SES effect on the percent increase associated with temperature.

Conclusions

The effects of high temperature on all deaths were modified by age and gender but not by SES in Brisbane, Australia.     

Community response to environmental noise and the impact on cardiovascular risk score

Objective

The objective of our study was to investigate and evaluate the relationship between road traffic noise and cardiovascular risk.

Methods

The study sample (n = 659; 36.9% male, 63.1% female university students, mean age 22.83 ± 1.58 years) included a group exposed to road traffic noise (n = 280, L_eq,24 h = 67 ± 2 dB(A)) and a control group (n = 379, L_eq,24 h = 58.7 ± 6 dB(A)). Subjective response was determined by a validated noise annoyance questionnaire. The ten year risk of developing a coronary heart disease event was quantified as an evaluation of cardiovascular risk (SCORE60, Framingham 10-year risk estimation and projection to the age of 60, relative risk SCORE chart).

Results

Cardiovascular risk scores were significantly higher in the exposed group based on the Framingham scores projected to the age of 60, SCORE60 (AOR = 2.72 (95% CI = 1.21-6.15)) and the relative risk SCORE chart (AOR = 2.81 (1.46-5.41)).

Conclusions

These findings highlight the association between road traffic noise and cardiovascular risk.