搪玻璃设备修补技术及应用实例

搪玻璃设备在使用中易造成局部损坏 ,现国内外多采用美国贝尔佐纳陶瓷金属进行修补 ,陶瓷R金属作底层 ,根据介质、温度分别用S金属、高温金属、超高温金属为面层。根据操作压力、穿孔大小 ,采用直接涂料、增强带、贴钢板技术进行修补。

Effect of sintering atmosphere on corrosion resistance of Ni/(NiFe_2O_4-10NiO) cermet inert anode for aluminum electrolysis

A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 （volume fraction） are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer （about 50 μm） is thicker than that （about 30 μm） formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe（II） in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.

Effect of additive BaO on corrosion resistance of xCu/(10NiO-NiFe_2O_4) cermet inert anodes for aluminum electrolysis

xCu/（10NiO-NiFe2O4） cermet and 1BaO-xCu/（10NiO-NiFe2O4） cermet（x=5,10,17） inert anodes were prepared as potential inert anodes for aluminum electrolysis and their corrosion resistance to traditional electrolyte was studied with anodic current density of 1.0 A/cm2 in laboratory electrolysis.The substantial corrosion of metal Cu was observed,many pores appeared on the surface of anode and electrolytes infiltrated inside anodes during the electrolysis.The wear rates of 5Cu/（10NiO-NiFe2O4）,10Cu/（10NiO-NiFe2O4）,17Cu/（10NiO-NiFe2O4）,1BaO-5Cu/（10NiO-NiFe2O4）,1BaO-10Cu/（10NiO-NiFe2O4） and 1BaO-17Cu/（10NiO-NiFe2O4） are 2.15,6.50,8.30,4.88,4.70 and 4.48 cm/a,respectively.The addition of BaO to 10Cu/（10NiO-NiFe2O4） cermet and 17Cu/（10NiO-NiFe2O4） cermet is advantageous because BaO can effectively promote densification and thus improve corrosion resistance.But the addition of BaO to 5Cu/（10NiO-NiFe2O4） cermet is unfavorable to corrosion resistance because additive BaO at the grain boundary of anode accelerates possibly the corrosion of cermet.

搪玻璃设备修补技术及应用

搪玻璃设备在使用中易造成局部损坏 ,现国内外多采用美国贝尔佐纳陶瓷金属进行修补 :陶瓷R金属作底层 ,根据介质、温度分别用陶瓷S金属、高温金属、超高温金属为面层 ;根据操作压力、穿孔大小 ,采用直接涂料、增强带、贴钢板技术进行修补。

Effect of VC/Cr_3C_2 on microstructure and mechanical properties of Ti(C,N)-based cermets

Effects of VC/Cr3C2 on the microstructure and mechanical properties of Ti（C,N）-based cermets were studied. The microstructure was investigated by means of optical microscopy, X-ray diffractometry as well as scanning electron microscopy in combination with energy dispersive spectrometry. Mechanical properties, such as transverse rupture strength, hardness and fracture toughness, were measured. The results show that there are black core-grey rim structure and white core-grey rim structure in the microstructure. The grains become fine due to the VC/Cr3C2, and the grains of cermet added with 0.75VC/0.25Cr3C2 are refined most remarkably. The black core becomes finer with the increase of VC addition and rim phase becomes thicker with the decrease of Cr3C2 addition. The porosity increases with the increase of VC addition in VC/Cr3C2. Compared with the cermet free of VC/Cr3C2, the transverse rupture strength and hardness of cermets with VC/Cr3C2 are both improved, and the maximum values are both found for the cermet with 0.25VC/0.75Cr3C2. The fracture toughness can be effectively promoted by adding VC/Cr3C2 with an appropriate ratio of VC to Cr3C2, and the maximum value is found for the cermet with 0.5VC/0.5Cr3C2.

An Experimental Study of Cutting Performance of Ti(C, N) Based Cermet Cutting Tool

Through systematic cutting experiments, characteristics of the cutting performance of Ti(C, N) based cermets is identified. The experiments were designed to study their resistance,toughness, cutting force, tool-chip friction coefficient and machining quality by comparing them with those of WC based cemented carbides. The cutting data and the regressed empirical formulae would be useful to promote proper application of cermet cutting tool materials.

Effect of sintering atmosphere on phase composition and mechanical properties of 5Ni/(10NiO-NiFe_2O_4)

5Ni/（10NiO-NiFe2O4） cermet materials were prepared by cold pressing sintering method in different atmospheres. The phase compositions were studied by XRD, microstructure was studied by SEM and mechanical properties were studied by three-point-bending strength and heat cycle. The results show that Ni/（NiO-NiFe2O4） cermet can be obtained by sintering in vacuum or atmospheres with oxygen content of 2×10-5, 2×10-4 and 2×10-3, respectively, but the phase composition of the ceramics varies greatly with oxygen content of the sintering atmosphere. The cermet tends to have a high content of NiO when sintered in vacuum. The content of NiFe2O4 and Ni in the cermet materials respectively increases and decreases with increasing oxygen in the sintering atmosphere. In the vacuum, cermet has an average grain size of 3.90 μm and bending strength of 138.59 MPa, which is able to withstand thermal shock tests 6.67 times in average.

Thermal properties of pressureless melt infiltrated AlN-Si-Al composites

Thermal properties of AlN-Si-Al composites produced by pressureless melt infiltration of Al/Al alloys into porous a-Si3N4 preforms were investigated in a temperature range of 50-300 °C. SEM and TEM investigations revealed that the grain size of AlN particles was less than 1 μm. In spite of sub-micron grain size, composites showed relatively high thermal conductivity （TC）, 55-107 W/（m·K）. The thermal expansion coefficient （CTE） of the composite produced with commercial Al source, which has the highest TC of 107 W/（m·K）, was 6.5×10-6 K-1. Despite the high CTE of Al （23.6×10-6 K-1）, composites revealed significantly low CTE through the formation of Si and AlN phases during the infiltration process.

Microstructures and properties of PVD TiAlN coating deposited on cermets with different Ti(C,N)grain size

In the present work,TiAlN coatings were deposited on Ti(C,N)-based cermet substrates by physical vapor deposition method.Emphasis was focused on the influence of grain size of cermet substrates on the microstructure,growth behavior,mechanical properties,adhesion strength and wear behavior of the coatings.The results show that finer Ti(C,N)grain size leads to higher nucleation density and lower growth rate of coatings,indicating the crystallite size of the TiAlN coatings decreases with decreasing Ti(C,N)grain size.Nanoindentation tests show that the coatings deposited on cermets of the finest grain size exhibit the highest hardness(H),elastic modulus(E),H/E and H3/E2 of 34.5 GPa,433.2 GPa,0.080 and 0.22,respectively.The adhesion strength between coating and substrate is also enhanced with decreasing Ti(C,N)grain size by scratch test,which corresponds to the grain size and H/E and H3/E2 of the coating.Besides,the lower surface roughness and better mechanical properties of the coating deposited on finer grained cermet contribute to the better wear resistance of the coating.

Microstructure and mechanical properties of WC-Co,WC-Co-Cr_3C_2 and WC-Co-TaC cermets fabricated by spark plasma sintering

Spark plasma sintering was successfully used to produce WC-Co cermets with the addition of Cr3C2and TaC grain growth inhibitors. The spark plasma sintered compacts were investigated by scanning electron microscopy, X-ray diffraction analysis, density measurements, hardness tests, fracture toughness tests and elastic modulus tests. The results were comparedwithan inhibitor-free WC-Co cermet consolidated under the same process parameters. By using Cr3C2and TaC additives, it is possible to improve the hardness and fracture toughness of WC-Co cermets, but Cr3C2has better grain growth inhibition propertythan that of TaC. The best combination of hardness （HV30（2105±38）） and fracture toughness （（8.3±0.2）MPa·m^1/2） was obtained by the WC-5Co-2Cr3C2 cermet.

Effect of sintering atmosphere on composition and properties of NiFe_2O_4 ceramic

Ni Fe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound Ni Fe2O4 cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10-5, 2×10-4 and 2×10-3, respectively. All the samples sintered in above-mentioned atmospheres contain phases of Ni Fe2O4 and Ni O. With increasing oxygen content, Ni Fe2O4 content in the ceramic increases, while Ni O content appears a contrary trend. In vacuum, Ni Fe2O4 ceramic has average grain size of 3.94 μm, and bending strength of85.12 MPa. The changes of the phase composition and mechanical properties of Ni Fe2O4 based cermets are mainly caused by the alteration of their properties of Ni Fe2O4 ceramic.

Hydrogen Permeation Performance of Ni-BaZr0.1Ce0.7Y0.2O3-δ Metal-Ceramic Hollow Fiber Membrane

Acknowledgment： This work was supported by the National Natural Science Foundation of China （No.21076204） and the Basic Research Foundation

Research on the cutting performance and the wear mechanism of the cermet cutter in high speed turn-milling

When machining D60 steel by high speed turn-milling under the different cooling and lubricating conditions, the cutting performance and the wear mechanism of the cermet cutter are researched. With water soluble cooling fluid, the wear performance of the cermet cutter is bad, and does not adapt to the requirements of machining. However, when machining D60 by high speed turn-milling is under dry conditions, the wearing performance of the cermet cutter is very good and the cutting time lasts almost 3 hours. The wear mechanism of the cermet cutter under the water soluble cooling fluid is different from the dry condition. With the water soluble cooling fluid, a great deal of little chap units are formed since high frequency alternates heat stress. The crash and desquamate of these chap units is the main cause of the cutter wearing. Under dry cutting conditions, it is the main cause of cermet cutter wear in the felting phase intenerating causing rigid phase grains to fall.

Effects of pretreatment and HVOF sprayed cermet coating on fatigue properties of TC21 titanium alloy

The effects of grit blasting (GB),shot peening (SP) pretreatment and high velocity oxygen fuel(HVOF) sprayed WC-17Co cermet coating on the fatigue properties of the novel ultra-high strength TC21 titanium alloy were investigated with a rotating bending fatigue test machine.The basic properties and surface integrity of the coating were investigated by using X-ray diffraction (XRD),surface roughness meter,microscopic hardness tester,scanning electron microscopy (SEM) and X-ray stress test instruments.The results showed that the residual compressive stress could be introduced into the surface of TC21 alloy by GB and SP pretreatment,and that HVOF sprayed WC-17Co coating was compactly bonded with TC21 alloy substrate and it significantly improved the surface hardness of the substrate.However,there was a certain residual tensile stress in the sublayer of the coating.SP could significantly increase fatigue resistance of TC21 alloy due to the surface residual compressive stress.There was no significant effect on fatigue resistance by GB treatment due to the offset between the influence of surface residual compressive stress and the surface notch effect.The fatigue resistance of TC21 alloy was significantly reduced by HVOF WC-17Co coating prepared with GB pretreatment.This could be attributed to the relaxation of surface residual compressive stress during the HVOF heating process,pore defects and residual tensile stress distribution in the WC-17Co coating with low toughness,and the surface notch induced by GB.The fatigue resistance of TC21 alloy was slightly reduced by HVOF WC-17Co coating prepared with SP pretreatment.This was attributed to the offset between the advantage effect by SP and disadvantageous effect of WC-17Co coating and high temperature factor during the HVOF process.