The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the h...The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous- nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.展开更多
In recent years, spark plasma sintering technique(SPS) has been a focus in the field of material preparation due to its advantages. SPS technique is first introduced for preparation of high quality NdFeB magnets. The ...In recent years, spark plasma sintering technique(SPS) has been a focus in the field of material preparation due to its advantages. SPS technique is first introduced for preparation of high quality NdFeB magnets. The effects of heat treatment process on the magnetic properties of SPS NdFeB magnet were investigated. Meanwhile, the effects of heat treatment process on the microstructure, tropism and dimensional precision of the SPS NdFeB magnets were also studied. The high quality NdFeB magnets with fine grains were prepared under proper heat treatment process. The results show that the magnetic properties of SPS NdFeB can be further improved through proper heat treatment process. Meanwhile, the experiment also demonstrates that it is feasible to prepare near net shape NdFeB magnets with fine grains and high magnetic property by spark plasma sintering.展开更多
It has been reported by previous research work that in plasma spray process hydroxyapatite decomposes into some amorphous phases due to rapid cooling of the coated substrate during the coating process, which causes in...It has been reported by previous research work that in plasma spray process hydroxyapatite decomposes into some amorphous phases due to rapid cooling of the coated substrate during the coating process, which causes instability of coated implant. Post coating heat treatment has been expected to minimize these phases and also enhance the long term reliability of hydroxyapatite coatings on metal substrates. In this paper post coating heat treatment is carried out at different temperatures suggested by the literature to study its effect on the microstructural and mechanical properties of coating. Coated substrates were characterized by X-ray diffraction (XRD) and SEM/EDAX analysis.展开更多
The Si3N4 microcrystals with a hollow sphere structure were prepared by using the simple heat treatment of the Si3N4 flakes, which were prepared by using the cathode arc plasma. The products were characterized by XRD,...The Si3N4 microcrystals with a hollow sphere structure were prepared by using the simple heat treatment of the Si3N4 flakes, which were prepared by using the cathode arc plasma. The products were characterized by XRD, SEM and TEM. The photoluminescence (PL) spectrum of the Si3N4 nano-microsphere was studied. The obtained Si3N4 microcrystals, which show a hollow sphere structure, are up to several nanometers in diameter. During the process, the heat treatment and Ni catalyst play a key role in the forming structure and morphology. This result provides a possibility for mass producing Si3N4 microcrystals.展开更多
FeCoCrNiAl high entropy alloy coatings were prepared by supersonic air-plasma spraying.The coatings were post-treated by vacuum heat treatment at 600 and 900°C,and laser re-melting with 300 W,respectively,to stud...FeCoCrNiAl high entropy alloy coatings were prepared by supersonic air-plasma spraying.The coatings were post-treated by vacuum heat treatment at 600 and 900°C,and laser re-melting with 300 W,respectively,to study the influence of different treatments on the structure and properties of the coatings.The phase constitution,microstructure and microhardness of the coatings after treatments were investigated using X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry.Results showed that the as-sprayed coatings consisted of pure metal and Fe-Cr.The AlNi;phase was obtained after the vacuum heat treatment process.A body-centered cubic structure with less AlNi;could be found in the coating after the laser re-melting process.The average hardness values of the as-sprayed coating and the coatings with two different temperature vacuum heat treatments and with laser re-melting were 177,227,266 and 682 HV,respectively.This suggests that the vacuum heat treatment promoted the alloying process of the coatings,and contributed to the enhancement of the coating wear resistance.The laser re-melted coating showed the best wear resistance.展开更多
基金Funded by the Basic Scientific Research of Central Colleges,Chang’an University (No. CHD2011JC126)
文摘The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous- nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.
文摘In recent years, spark plasma sintering technique(SPS) has been a focus in the field of material preparation due to its advantages. SPS technique is first introduced for preparation of high quality NdFeB magnets. The effects of heat treatment process on the magnetic properties of SPS NdFeB magnet were investigated. Meanwhile, the effects of heat treatment process on the microstructure, tropism and dimensional precision of the SPS NdFeB magnets were also studied. The high quality NdFeB magnets with fine grains were prepared under proper heat treatment process. The results show that the magnetic properties of SPS NdFeB can be further improved through proper heat treatment process. Meanwhile, the experiment also demonstrates that it is feasible to prepare near net shape NdFeB magnets with fine grains and high magnetic property by spark plasma sintering.
文摘It has been reported by previous research work that in plasma spray process hydroxyapatite decomposes into some amorphous phases due to rapid cooling of the coated substrate during the coating process, which causes instability of coated implant. Post coating heat treatment has been expected to minimize these phases and also enhance the long term reliability of hydroxyapatite coatings on metal substrates. In this paper post coating heat treatment is carried out at different temperatures suggested by the literature to study its effect on the microstructural and mechanical properties of coating. Coated substrates were characterized by X-ray diffraction (XRD) and SEM/EDAX analysis.
基金Project(60376039) supported by the National Natural Science Foundation of China
文摘The Si3N4 microcrystals with a hollow sphere structure were prepared by using the simple heat treatment of the Si3N4 flakes, which were prepared by using the cathode arc plasma. The products were characterized by XRD, SEM and TEM. The photoluminescence (PL) spectrum of the Si3N4 nano-microsphere was studied. The obtained Si3N4 microcrystals, which show a hollow sphere structure, are up to several nanometers in diameter. During the process, the heat treatment and Ni catalyst play a key role in the forming structure and morphology. This result provides a possibility for mass producing Si3N4 microcrystals.
基金financially supported by National Natural Science Foundation of China (Nos.51301112 and 51401129)China Postdoctoral Science Foundation (2015M571327)+1 种基金the Natural Science Foundation of Liaoning Province(No.201602553)the Science Research Program of Education Department in Liaoning Province(No.L2014048)
文摘FeCoCrNiAl high entropy alloy coatings were prepared by supersonic air-plasma spraying.The coatings were post-treated by vacuum heat treatment at 600 and 900°C,and laser re-melting with 300 W,respectively,to study the influence of different treatments on the structure and properties of the coatings.The phase constitution,microstructure and microhardness of the coatings after treatments were investigated using X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry.Results showed that the as-sprayed coatings consisted of pure metal and Fe-Cr.The AlNi;phase was obtained after the vacuum heat treatment process.A body-centered cubic structure with less AlNi;could be found in the coating after the laser re-melting process.The average hardness values of the as-sprayed coating and the coatings with two different temperature vacuum heat treatments and with laser re-melting were 177,227,266 and 682 HV,respectively.This suggests that the vacuum heat treatment promoted the alloying process of the coatings,and contributed to the enhancement of the coating wear resistance.The laser re-melted coating showed the best wear resistance.
