Three-way catalyst was prepared by isovolumetric impregnation with the scattered metal In,the transition metal Ag and the rare earth metal Ce as the active components andγ-Al2O3 as the carrier.The microstructure of the catalyst was characterized by XRD,BET,SEM and N2 adsorption technology.The influence of In content on catalyst performance was also investigated.The results show that the catalyst activity can be improved after In addition resulting in AgInO2 phase appearing in its XRD pattern.However,the catalyst activity gradually decreases with the increase of In content.The results from BET and SEM show that the increase of In content causes aggregation of the active ingredients to reduce their dispersion degree and decrease of the specific surface area of the catalyst to reduce its catalytic activity.In-Ag-Ce-O/γ-Al2O3 catalyst has the strongest three-way catalytic activity when its active ingredient In content is 2%.

The extrusion process of the alloy ingot NbHf10-1was studied.The results show that the extrusion ingot with good surface quality can be obtained when the extrusion ratio is lower than 5∶1and extrusion temperature is 980~1 320 ℃.Using the extrusion rectangular bar to roll NbHf10-1alloy sheet,both finished product ratio and production efficiency of rolling can be improved.

The effect was investigated of annealing temperature on room temperature and high temperature mechanical properties of Zr-4alloy different diameter pipe with different deformation(50% and 18% retransformation after the first annealing).Metallurgical microstructure was observed by optical microscope of the alloy with 50% deformation and 18%retransformation after the first annealing at 523 ℃for 3.5h.The results show that room temperature mechanical properties of Zr-4alloy different diameter pipe with50% deformation depend on its first annealing temperature,and that of the pipe with 18%retransformation after its first annealing depend on its second annealing temperature.When Zr-4alloy different diameter pipe with 50% and 18%retransformation after its first annealing is annealed at 540℃for 3.5h,it has the maximum high temperature elongation.After twice 523℃/3.5hannealing,the pipe with 50% deformation has typical equiaxed microstructure with completely recrystallized morphology.After once 523℃/3.5hannealing,the pipe with 18% retransformation has the microstructure of vague and disordered morphology,and its grains still have strong directionality with the typical morphology in stress-relief state.

Graded cemented carbide with beta free layer was fabricated with nitrogen free raw material by adding a sintering step of micro-pressure nitriding before gradient sintering.The microstructure of the surface layer of the graded cemented carbide was investigated by SEM and the depth of beta free layer was measured by an image analysis tool.The results show that with the added micro-pressure nitriding(0.5kPa N2 partial pressure),the graded cemented carbide No.Co-8sintered at 1 420℃,1 450℃and 1 480℃for 1hhas beta free layer depths of 8μm,13μm and 24μm,respectively.However,the beta free layer depth is close to zero of the graded cemented carbide No.Co-6sintered at 1 420 ℃,and its beta free layer depths are also significantly less than those of No.Co-8sintered at the other two sintering temperature.With the same sintering process,the beta free layer depth of the graded cemented carbide prepared with nitrogen free raw material is obviously lower than that with Ti(C,N)-containing raw material.

The metallurgical microstructure and physical properties of WC-8%Co cemented carbide were studied after sintering at 5MPa and 1 360 ℃,1 405 ℃ or 1 460 ℃for 90 min.The results show that with sintering temperature increasing,the hardness of the alloy gradually decreases,its density,flexural strength and fracture toughness gradually increase,its impact toughness increases at first and then decreases,and the number of its coarse grains gradually increases with plate-like shape.

High-speed continuous cutting test was carried out with different cobalt content of ultrafine cemented carbide tools to cut the superalloy GH2132.Based on linear regression of the test results with the least square method,the T-vcempirical formula was set up reflecting the relationship between tool life and cutting speed.And then tool wear test was carried out by high-speed intermittent cutting.Wear morphologies of tool edges and flank faces were observed with zoom stereomicroscope and photomicrography system.When the tool achieved the wear criterion,the composition of its flank wear micro-zone was analyzed by electron microprobe spectroscopy.The mechanism was discussed of cobalt content influencing tool wear resistance.The results show that both too high and too low cobalt content would result in poorer tool wear and breakage resistance.

Two kinds of ultrafine-grained WC-Co cemented carbides were chosen to fabricate micro-drills,and then 0Cr18Ni9 stainless steel was drilled with the fabricated micro-drills.The wear of micro-drills was observed and analyzed,and their working life was measured.The results show that for the micro-drills,the finer WC grains,the slower wear speed and the longer working life.Grain refinement is helpful for reducing chipping and breakage of the micro-drills during micro-drilling.

Cutting experiment of YG6 cemented carbide was carried out on a high speed WEDM machine tool.The influences were studied of such electrical parameters as pulse width,pulse gap,peak current and gap voltage on cutting speed and surface roughness of the cemented carbide.The machined surface of the cemented carbide has many pits,which are more apparent with increased pulse width and gap voltage.

In view of arsenic and ammonia nitrogen existing in wastewater from tungsten metallurgy and high alkalinity of the wastewater,principle,efficiency,advantages and disadvantages of various treatment methods are analyzed and reviewed.The treatment processes of ammonia nitrogen wastewater are mainly introduced,and their advantages and disadvantages are analyzed during application in tungsten metallurgy.It is pointed out that the combined process can deeply remove ammonia nitrogen,save energy consumption and avoid secondary pollution.And the development direction of wastewater treatment is discussed.

Experimental research was carried out on selective leaching of the valuable elements such as Ga,Al and K in gallium-containing alunite concentrate.Under the conditions of leaching temperature 80 ℃,leaching time 120 min,agitation speed 300r/min,H2SO4 concentration 70g/L and liquid to solid ratio4∶1,the leaching rates of Al and K are 81.7% and 89.1%,respectively,while the leaching rate of Ga is0.72%.Ga content in the leaching slag is 171.3g/t,which is 3.16 times as rich as the raw material,showing that Ga is separated from Al and K.