WIN95系统保护现状及探讨

在讲述国内ＷＩＮ９５系统保护现状的基础上,介绍一种ＷＩＮ９５系统的保护方案,并对其作了进一步的探讨。     

Frother function–structure relationship: Dependence of CCC95 on HLB and the H-ratio

Although the number and diversity of commercial frothers has steadily increased to meet flotation industry demands, frother selection is still mainly empirical. As part of a general structure–property study, the paper presents a correlation between the critical coalescence concentration (CCC95) and H-ratio for surfactants used as flotation frothers. The CCC95 were determined in 0.8 m³ mechanical flotation cell. The H-ratio was a substitution of hydrophile-lipophile balance (HLB) and determined through high resolution proton nuclear magnetic resonance (¹H NMR) spectrometry. A large data set, consisting of 45 surfactants from four frother families, was used to develop the correlation. It is shown that the H-ratio can substitute for HLB. The potential of NMR both to identify the frother family and to derive the H-ratio in predicting CCC95 for commercial frothers is discussed.     

Physiological and subjective responses to breathing resistance of N95 filtering facepiece respirators in still-sitting and walking

The objective of this study was to assess the impact of breathing resistance on physiological and subjective responses to N95 filtering facepiece respirators (N95 FFRs) during still-sitting and walking. Fifteen subjects sat for 5 min and walked for 5 min while wearing 2 different models of N95 FFRs, 1 model of which was equipped with exhalation valves (N95 FFR/EV). The subjects were monitored by a modified monitoring garment for respiratory signals (RSP) and surface electromyography (sEMG). Subjects also were asked to complete subjective ratings of overall breathing resistance. The results of the physiological measurements in this study have shown that compared with no respirator, wearing N95 FFR had a direct effect on increasing respiratory amplitude, muscle activity and fatigue of abdominal, and fatigue of scalene; The use of N95 FFR/EV conferred limited physiological benefit over N95 FFR in walking; Compared with sitting still, walking significantly decreased respiratory amplitude, but increased respiratory rate, the muscle activity of sternomastoid, scalene, diaphragm and abdominal, the fatigue of scalene and intercostal. The subjective survey showed that wearing respirators and walking had a direct effect on improving the subjective overall breathing resistance. Significantly low to moderate correlation coefficients were shown between physiological values (respiratory amplitude, the muscle activity of diaphragm, the muscle activity and fatigue of scalene and abdominal), and the subjective breathing resistance. This is the first reported study that combines RSP, sEMG and subjective overall breathing resistance to evaluate breathing resistance on the use of N95 FFR in sitting still and walking. The physiological responses to breathing resistance of wearing a N95 FFR for 5 min in still-sitting and walking are relatively small and should generally be well tolerated by healthy persons.Relevance to industryThis paper's findings can be readily employed by respirator manufactures and administrations for evaluating the respiratory muscle function (activity, fatigue) and breathing parameters of wearing N95 FFRs. Observations of present study are in support of issuing new regulations to raise the limit for breathing resistance over short periods at low-moderate exertion tasks. Thus, the manufacturers could easily fulfill the requirements for collection efficiency by adding more filter media while still meeting the requirements for air resistance.     

变质工艺对过共晶Al-Si合金连铸坯组织的影响

采用美国标准TP-1模具及模拟方法,研究了Al-Si-P变质剂的加入量、熔体浇注温度以及变质保温时间对过共晶Al-Si合金连铸坯料凝固组织的影响规律.结果表明,Al-Si-P变质剂加入量(超过0.02%)和变质保温时间对合金显微组织细化的影响不明显;而浇注温度对初生Si的大小分布影响较大,浇注温度越高,初生Si越细小、分布也越均匀.在合适的工艺匹配条件下,可以获得初生Si细小、形貌较为规则圆整、分布均匀的显微组织.     

FGH95镍基合金的蠕变行为及影响因素

通过蠕变曲线测定和组织形貌观察,研究FGH95合金的蠕变行为及影响因素。结果表明:经1150℃固溶和时效处理后,在晶界处有粗大γ′相不连续分布,其周围存在γ′相贫化区;经1165℃固溶和时效后,合金的晶粒尺寸明显长大,并在晶界形成连续的碳化物膜;经1160℃固溶后,合金中无粗大γ′相,在晶内弥散析出细小γ′相,其中,有粒状(Nb,Ti)C相在晶内及沿晶界不连续析出,可提高合金的晶界强度,抑制晶界滑移,是使合金具有较好蠕变抗力的主要原因。蠕变期间,合金的变形机制是位错剪切或绕过γ′相,蠕变后期,在晶内发生单取向和双取向滑移,并引起应力集中,致使裂纹在晶界处萌生及扩展是合金的蠕变断裂机制。     

镍基合金激光直接制造的显微组织与缺陷分析

采用FGH95镍基高温合金粉末进行激光直接制造工艺实验，研究了不同工艺参数对表面形貌、显微组织和显微硬度的影响。结果表明，成形件表面平整无变形，显微组织为细小而致密的柱状晶。有层内生长和外延式生长两种生长方式。同时对其中出现的缺陷也作了研究分析，得到了优化的工艺参数。     

挤压变形对Mg95Zn4.3Y0.7合金组织和性能的影响

研究了在250℃、不同挤压比下挤压变形对Mg95 Zn4.3 Y0.7合金组织及性能的影响。结果表明，Mg95 Zn4.3 Y0.7经过挤压变形后，合金中晶界处的共晶相破碎，弥散分布至晶粒内部，并且晶粒显著细化。同时，随着挤压比的增大，晶粒细化程度增加，合金的力学性能单调增加。当挤压比为16时，合金晶粒尺寸为5-8μm，抗拉强度为288.9MPa，显微硬度HV值为117.8。     

不同分散剂对水系流延氧化铝基片的影响

研究了2种不同类型的分散剂对水系流延氧化铝基片的影响。研究发现：从浆料的分散性、所流延坯片的质量、烧结后基片的密度及其微观结构的比较，流延氧化铝浆料以聚丙烯酸（PAA）为分散剂明显优于以阿拉伯树胶为分散剂。以阿拉伯树胶为分散剂的浆料分散性较差，流延出的坯片生坯密度较低、坯片的柔软性较差，烧结后相对密度较低，同时，由于分散剂对塑化剂的影响，使得粘结剂PVA在浆料中没有凝胶化，从而在坯片上表面产生C富集层。     

镍基粉末冶金FGH95高温合金的拉伸及低周疲劳性能研究

在420～650℃的温度范围内,研究了PM FGH95高温合金在应变率0.0001～0.01 s-1范围内的拉伸性能及在不同应力比R=-1及R=0下的低周疲劳性能.拉伸试验结果表明:在此温度范围内,应变率对弹性模量、拉伸屈服强度及塑性模量的影响可以忽略不计;并且应变率自0.0001 s-1增大至0.01 s-1时,弹性模量、拉伸屈服强度及塑性模量受温度的影响也不明显.PM FGH95合金受材料微结构的影响很大,材料含有的微缺陷对其力学性能有非常不利的影响.LCF试验结果表明:PM FGH95合金是循环硬化材料.当应力比R=-1时,温度对LCF寿命的影响很小;但在应力比R=0时,LCF寿命受温度的影响很大,且随着温度的增加材料的低周疲劳寿命减小.SEM断口扫描发现,断裂表面有很多的解理面,但没有疲劳条带,且此断裂模式下没有明显的塑性变形,所以FGH95合金的低周疲劳寿命几乎是由裂纹萌生阶段决定的.     

FGH95合金铸锭均匀化处理工艺研究

采用热处理和等温压缩两种工艺对FGH95合金铸锭的均匀化处理进行了研究,分析了FGH95合金铸锭均匀化处理前后的枝晶组织变化及微区成分变化。结果表明:FGH95合金铸锭存在严重的枝晶偏析,经1170℃×20h均匀化处理或在1150℃等温压缩70%后,合金铸锭的组织和成分达到均匀化,铸锭内的枝晶偏析得以消除,并且1150℃等温压缩70%工艺比1170℃×20h工艺所得的组织更加细小,晶粒平均尺寸约为85.28μm。