鄂尔多斯盆地周边地区野外溶蚀试验结果讨论

2003到2004年,在国土资源部地质调查项目“鄂尔多斯盆地地下水勘查”工作中,作者在鄂尔多斯盆地周边地区建立了8个野外溶蚀试验站,采用不同岩石的600多枚试片开展了为期1年的野外溶蚀试验观测。通过试验并结合前人的野外溶蚀试验成果分析,得出了如下几个重要的结论: ( 1)试验区灰岩较白云岩的溶蚀量大20%以上; ( 2)与我国南方的试验结果相反,即北方土下碳酸盐岩样品溶蚀量远远小于地上样品的溶蚀量; ( 3)从华北到西北存在一个碳酸盐岩样品由溶蚀变为沉淀的地带;同理,从我国北方碳酸盐岩样品土下溶蚀量小于地上溶蚀量到南方土下溶蚀量大于地上溶蚀量区域变化过程中,又存在土下与地上溶蚀量接近的地带,这两个地带是控制我国现代岩溶作用机制的重要分界线,对岩溶地貌的发育与演化研究具有重要意义。      

氧化铬对铝型材厂碱蚀渣制备铝方柱石材料结构的影响

利用铝型材厂碱蚀渣为主要原料,采用二步煅烧工艺制备铝方柱石材料。探索二次煅烧温度对铝型材厂碱蚀渣制备铝方柱石材料相组成、结晶度、微观结构的影响,进而研究氧化铬对铝方柱石材料相组成、微观结构的影响。采用同步热分析、X射线衍射、扫描电镜及相关分析软件表征制备的铝方柱石材料的相组成和显微结构。结果表明：铝型材厂碱蚀渣中有大量可烧失成分,物料需要进行致密化处理,再经过1500℃煅烧后的铝方柱石材料结构中具有明显的铝方柱石条柱状结构,结晶度增大,铝方柱石相对含量达到91%。随着氧化铬加入量增加,结构中的铝铬酸钙相增加。当氧化铬加入量为2%时,试样中结晶相的结晶度最高,形成条柱状铝方柱石相与立方状铝铬酸钙相共存的结构。当氧化铬加入量4%时,试样中铝方柱石相几乎消失,结晶度降低。     

Mg2B2O5晶须增强AZ91D镁基复合材料在Cl-溶液中腐蚀行为*

用电化学方法测量了Mg_2B_2O_5晶须增强AZ91D镁基复合材料在3.5%NaCl溶液中的开路电位、动电位极化曲线和交流阻抗,研究了晶须体积分数对镁合金基体耐腐蚀性能的影响,并利用SEM和XRD表征了腐蚀后复合材料表面的微观形貌和相组成。结果表明,随着Mg_2B_2O_5晶须体积分数的增加,AZ91D镁基复合材料的耐腐蚀性逐渐提高。当硼酸镁晶须的体积分数为35%时,材料的自腐蚀电位提高0.2V以上,自腐蚀流密度降低了1个数量级;SEM测试表明,复合材料表面生成了一层晶须增韧的腐蚀钝化膜,对基体起到保护作用。     

Experimental study on the effect of the critical temperature of water on the preparing and occurring of large earthquakes

The features of fracturing and dissolving of Yunnan marble in distilled water near the critical temperature have been studied experimentally. The results indicate that the mechanical parameters of the samples (fracture strength, Young’s Modulus, shear fracture energy and fracture toughness) drop with the temperature of the environment water, near the critical temperature (380°C), these parameters have sudden changes (drop), then keep stable values roughly. The contents of some chemical materials in the water, PH value and conductivity at every experiment temperature have been analysed and measured. At 380°C, there all exist sudden changes. According to the results, it is pointed out that the sudden changes are related to strong stress corrosion of water near its critical temperature to the rock and the exist and its migration of the water solution near the critical temperature in the crust have important significance to the earthquake source process, the formation cause of the low-focal depth earthquakes in the crust. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 156–163, 1992. This work was sponsored by the Chinese Joint Seismological Science Foundation.     

Stress-induced crack path in Aji granite under tensile stress

The double-torsion test using Aji granite was carried out to investigate the interaction between stress-induced crack path and mineral grains. Crack velocities were controlled at range 10^–7 m/s to 10^–1 m/s. After the stressed specimens were dyed, we checked the crack path by thin section analysis, using an optical microscope. The stress-induced crack path was divided into two types, transgranular and intergranular cracks, and each path was subdivided with respect to mineral grains. In spite of the extensive range of crack velocities, the ratios between the transgranular and intergranular crack lengths did not change. The crack paths were all jagged, and often showed detour around the grain boundary when faced with obstacles like hard grains or preexisting cracks. That is to say, quartz grain played an important role as an obstacle. Feldspar grain could change the crack path because of its cleavage plane. Biolite grain had a serious effect on the path even if its constitution ratio is very small. Fractal dimensions of the crack paths were calculated by three methods, as indicators of surface roughness. The fractal dimensions were shown in a slight trend with the change of crack velocity. This trend can be explained from the point of limited cracking rate in stress corrosion.     

南极冰钻钻井液应用性试验研究

钻井液的性质及性能参数对于南极科学钻探有着重要的影响。钻井液除了必须要具备合适的粘度和密度,以满足冷却钻头、平衡孔壁压力、携带冰屑、清洁孔底的要求外,钻井液的性质如导电性、导热性及其腐蚀性对于保证钻具的正常工作、输送孔内信息也有着重要的影响。根据目前已经在南极使用的钻井液类型,分别对6种介质（国产硅油-3cst、KF96硅油-2cst、丁酸乙酯、丁酸丁酯、丁酸戊酯、丙酸丙酯）在不同温度下的电导率、导热系数和对密封件的腐蚀性进行了试验测试,选出了适合南极应用的钻井液类型及在钻具中使用的密封件材质,可供极地钻探选择钻井液类型及钻具设计提供重要的参考。     

贵州猫场超大型铝土矿床成因浅析

猫场铝土矿床位于大威岭背斜北东端猫场穹窿背斜。由于寒武系碳酸盐岩古喀斯特侵蚀面,经长期风化溶蚀淋滤作用,在古喀斯特正地形上先形成粘土层,粘土层进一步风化溶蚀经脱硅、脱铁形成三水铝石的矿源层,而古喀斯特负地形则为铝土矿的沉积提供了充足的场所。本文通过对含矿岩系的特征分析,结合沉积相与古地理环境等研究,揭示了猫场铝土矿床的形成严格受大地构造和古喀斯特地形的控制。     

Seawater Corrosion Fatigue of Welded Joints Under Random Variable Amplitude Loading

- Offshore platforms are always subjected to wave action which is random variable amplitude cyclic loading. In order to simulate the stressing condition at the 'hot spot' of the tubular joints and the marine environment, random variable amplitude fatigue tests have been carried out on welded plate joints in sea water. The tests have been conducted under the conditions of loading frequency of 0.2 Hz, stress ratio of -1, seawater temperature of about 20℃ and cathodic protection with the potential about -850 mV, SCE. The test results have been compared with the seawater corrosion fatigue life under constant amplitude loading. Miner's linear cumulative damage summation rule has been used to predict the corrosion fatigue life under variable amplitude loading. The predicted life is in good agreement with the test data.     

LF4铝合金在海水中的腐蚀性能研究

对艇用铝材LF4及其它多种管系金属材料进行静态和动态条件下的自然电位、自然腐蚀率、电化学性能、电偶腐蚀行为等进行多方面的腐蚀试验，得出这些材料在静态和动态海水中的腐蚀性能指标以及变化规律。随着海水流速的增加，LF4铝合金耐蚀性迅速降低。LF4在天然海水中有钝化的趋势，但是钝化膜不完整易破坏。在与其它常用管系金属材料组成的电偶对中，LF4均作为阳极受到加速腐蚀。