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430results about How to "Reduced compressive strength" patented technology

Punching-shear composite drill bit for hard rock drilling

The invention discloses a punching-shear composite drill bit for hard rock drilling. The punching-shear composite drill bit comprises three parts of an impactor, an internal punching bore bit and an external cutting drill bit, a lower joint of the impactor can be in threaded connection with the external cutting drill bit, and the upper part of the internal punching bore bit is connected with the impactor in a spline mode; and the lower end face of the internal punching bore bit extends out of the surface of the external cutting drill bit, the central axis of the internal punching bore bit is parallel to or coincident with the central axis of the external cutting drill bit, distributed teeth on the internal punching bore bit and distributed teeth on the external cutting drill bit are combined and can completely cover a downhole, and distributed teeth on the internal punching bore bit and the distributed teeth on the external cutting drill bit are independent of each other. In this way,rock crushing through shearing and rock crushing through impact are creatively combined together, a rock stratum at the hole bottom is pre-cracked first through the internal punching bore bit, the whole tectonic stress of the rock stratum is destroyed, the strength of compression resistance and shearing resistance of rock is reduced so that PDC column teeth and PDC cone teeth can more easily cut / plough-cut the rock, and the rock-breaking efficiency of the super hard rock stratum is greatly improved.
Owner:XIAN RES INST OF CHINA COAL TECH& ENG GROUP CORP

Multi-main-phase Nd-Fe-B type permanent magnet with high crack resistance and high coercive force and preparation method thereof

The invention pertains to the technical field of rare earth magnetically hard material, in particular to a multi-main-phase Nd-Fe-B type permanent magnet with high crack resistance and high coercive force and a preparation method thereof.A final magnet contains multiple differently-sized hard-magnetic main-phase particles having different anisotropic fields HA. Different main-phase particles account for different volume fractions and are differently distributed, wherein Nd denotes a red earth element having the most content based on the mass percent. According to mass percent, the chemical formula of the permanent magnet is expressed as (Dd, Re) aFe100-a-b-cBbTmc. By respective selection, different types of main-phase materials such as (Nd, Pr)-Fe-B, (PR, La, Ce)-Fe-B, (Dy, Tb, Ho, Gd, Er)-Fe-B in the ratio of 2:14:1 in order to prepare corresponding coarse magnetic powder, thin magnetic powder and magnetic nanocrystalline powder. Power is utilized for absorbing hydrogen and controlling oxygen. Liquid-phase sintering technology on the pressurized condition at low temperature is adopted for preparation. The multi-main-phase Nd-Fe-B type permanent magnet with high crack resistance and high coercive force and the preparation method thereof have following beneficial effects: a large piece of magnet does not easily have crack; crack resistance of the magnet is improved; high coercive force and high magnetic energy product are obtained; and the preparation technology is suitable for scale production in engineering.
Owner:CENT IRON & STEEL RES INST

Harmless treatment method for electroplating sludge

The invention belongs to the technical filed of environmental protection engineering and particularly relates to a harmless treatment method for electroplating sludge. The harmless treatment method comprises the following steps: the electroplating sludge is taken, certain amount of quicklime and flue gas desulfurization gypsum is added, crushed sufficiently and stirred uniformly, the mixture is left to stand for a period of time, and modified electroplating sludge is obtained; the modified electroplating sludge and fly ash are taken and stirred uniformly, a certain amount of a composite activator is added and stirred sufficiently again, and a mixture is obtained; an electroplating sludge test block is obtained in a pressure forming manner and cured in a room-temperature environment for 7-28 days, and a solidified electroplating sludge body is obtained. The harmless treatment method adopted for treating the electroplating sludge has the advantages of simple process, low cost, large electroplating sludge curing amount, small capacity increase and the like, meanwhile, the solidified electroplating sludge body obtained after treatment is highly corrosion-resistant, stable for a long time and low in heavy metal leaching toxicity, has certain compressive strength and can be taken as general solid waste to be subjected to landfill treatment.
Owner:SAFECLEEN TECH
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