To provide theoretical basis and practical guidance for preparing composite rods by direct continuous casting, copper-clad aluminum composite rods of external copper layer diameter 12 mm and inner aluminum core diamet...To provide theoretical basis and practical guidance for preparing composite rods by direct continuous casting, copper-clad aluminum composite rods of external copper layer diameter 12 mm and inner aluminum core diameter 8 mm were manufactured. Orthogonal tests consisted of three factors and three levels were carried out to research the effects of melting copper temperature, continuous casting speed and nitrogen pressure on the performance of composite rods. Results showed that nitrogen pressure is the most important factor in influencing the surface quality; continuous casting speed is the most important factor in influencing copper & aluminum inter diffusion amount. Nitrogen pressure can noticeably improve the surface quality and make the rods easily be drawn out, but the surface quality does not show visible improvement when the nitrogen pressure is above 0.05 MPa. Measured by tests, the compound layer can be divided into three types according to its cladding layer degree: deficient cladding, normal cladding and excess cladding. The diameter of normal copper-clad aluminum composite rods can be successfully drawn less than 0.6 mm without annealing.展开更多
The tarnishing test in the presence of hydrogen sulfide（H2S） vapors has been used to investigate the tarnish resistance capability of copper-based alloys coated with Si02-like films by means of plasma-enhanced chemi...The tarnishing test in the presence of hydrogen sulfide（H2S） vapors has been used to investigate the tarnish resistance capability of copper-based alloys coated with Si02-like films by means of plasma-enhanced chemical vapor deposition（PECVD） fed with a tetraethoxysilane/oxygen mixture.The chemical and morphological properties of the films have been characterized by using infrared absorption spectroscopy（IR） and scanning electron microscopy（SEM）with energy disperse spectroscopy（EDS）.The corrosion products of the samples after the tarnishing test have been identified by X-ray diffraction analysis（XRD）.It has been found that SiO2-like films formed via PECVD with a high O2 flow rate could protect copper-based alloys from H2S vapor tarnishing.The alloys coated at the O2 flow rate of 20 sccm remain uncorroded after 54days of H2S vapor tarnish testing.The corrosion products for the alloys deposited at a low O2flow rate after 54 days of tarnish testing are mainly composed of brochantite.展开更多
Recently a research team at Ohio University,USA,conducted a unique full-scale feld load test to simulate the aeration pipe installations at a copper extraction mine operated in Chile.The overliner material taken from ...Recently a research team at Ohio University,USA,conducted a unique full-scale feld load test to simulate the aeration pipe installations at a copper extraction mine operated in Chile.The overliner material taken from the mine was used in recreating the in situ conditions.Electric heaters were utilized to raise the temperature inside each pipe to simulate the essential element of the copper extraction process.The maximum vertical deflection reached by the test pipes was close to 20%,when the simulated heap pile height was 80 m.The plastic pipes and the overliner material were also tested in the laboratory.Based on the results,the maximum heap pile fll depth was recommended for the aeration system.The results indicated that the vertical deflection was the primary performance index for the aeration pipes installed in heap piles at mines.Lastly,the pipe made of polypropylene resin was super.展开更多
基金financially supported by the Program for New Century Excellent Talents in University(NCET-12-0849)the Fundamental Research Funds for the Central Universities(13ZD12)the National Natural Science Foundation of China(No.51006034)
文摘To provide theoretical basis and practical guidance for preparing composite rods by direct continuous casting, copper-clad aluminum composite rods of external copper layer diameter 12 mm and inner aluminum core diameter 8 mm were manufactured. Orthogonal tests consisted of three factors and three levels were carried out to research the effects of melting copper temperature, continuous casting speed and nitrogen pressure on the performance of composite rods. Results showed that nitrogen pressure is the most important factor in influencing the surface quality; continuous casting speed is the most important factor in influencing copper & aluminum inter diffusion amount. Nitrogen pressure can noticeably improve the surface quality and make the rods easily be drawn out, but the surface quality does not show visible improvement when the nitrogen pressure is above 0.05 MPa. Measured by tests, the compound layer can be divided into three types according to its cladding layer degree: deficient cladding, normal cladding and excess cladding. The diameter of normal copper-clad aluminum composite rods can be successfully drawn less than 0.6 mm without annealing.
基金supported by the Special Fund for Talent of Wuhan Institute of Technology,China(No.237127)the"Fellowship for Junior Researchers"from Politecnico di Torino and Regione Piemonte,Italy
文摘The tarnishing test in the presence of hydrogen sulfide（H2S） vapors has been used to investigate the tarnish resistance capability of copper-based alloys coated with Si02-like films by means of plasma-enhanced chemical vapor deposition（PECVD） fed with a tetraethoxysilane/oxygen mixture.The chemical and morphological properties of the films have been characterized by using infrared absorption spectroscopy（IR） and scanning electron microscopy（SEM）with energy disperse spectroscopy（EDS）.The corrosion products of the samples after the tarnishing test have been identified by X-ray diffraction analysis（XRD）.It has been found that SiO2-like films formed via PECVD with a high O2 flow rate could protect copper-based alloys from H2S vapor tarnishing.The alloys coated at the O2 flow rate of 20 sccm remain uncorroded after 54days of H2S vapor tarnish testing.The corrosion products for the alloys deposited at a low O2flow rate after 54 days of tarnish testing are mainly composed of brochantite.
文摘Recently a research team at Ohio University,USA,conducted a unique full-scale feld load test to simulate the aeration pipe installations at a copper extraction mine operated in Chile.The overliner material taken from the mine was used in recreating the in situ conditions.Electric heaters were utilized to raise the temperature inside each pipe to simulate the essential element of the copper extraction process.The maximum vertical deflection reached by the test pipes was close to 20%,when the simulated heap pile height was 80 m.The plastic pipes and the overliner material were also tested in the laboratory.Based on the results,the maximum heap pile fll depth was recommended for the aeration system.The results indicated that the vertical deflection was the primary performance index for the aeration pipes installed in heap piles at mines.Lastly,the pipe made of polypropylene resin was super.
