氧化釔穩(wěn)定氧化鋯摻雜鎢基合金的組織和性能研究
發(fā)布時間：2019-04-11 20:34
【摘要】：鎢合金廣泛應(yīng)用在國防,醫(yī)療,航天等領(lǐng)域,可以用來制作硬質(zhì)合金、鑄模、穿甲彈芯、電解觸頭和電極等產(chǎn)品。氧化鋯(ZrO_2)是一種化學(xué)性質(zhì)非常穩(wěn)定的材料,硬度和熔點極高,具有優(yōu)良的熱性能、機械性能、電性能及較高的耐磨損、耐腐蝕性,在機械子工業(yè)、航空工業(yè)等許多領(lǐng)域得到廣泛應(yīng)用。結(jié)合ZrO_2和W的優(yōu)異性能,可以提升鎢合金的室溫和高溫力學(xué)性能,因此開發(fā)出一種新型的ZrO_2摻雜鎢合金材料成為一項重要研究。通過液-液的摻雜方式,即分別采用水熱法和共沸蒸餾法結(jié)合傳統(tǒng)粉末冶金的方法制備了氧化鋯摻雜鎢合金粉末,并通過壓制成型,垂熔燒結(jié),旋鍛加工等工序制備出鎢合金材料。對合金制備過程中不同階段的物質(zhì)元素組成,相結(jié)構(gòu)轉(zhuǎn)變,微觀組織形貌進行分析,以及對合金性能進行分析。在水熱法制備粉體過程中,pH值和ZrO_2的摻雜量對前驅(qū)粉體的形貌和粒徑有著顯著影響。當(dāng)pH=0.5時,顆粒最為細小。ZrO_2的摻雜量增加,前驅(qū)粉體易發(fā)生結(jié)塊團聚現(xiàn)象。煅燒后粉體由單斜相氧化鎢(m-WO3)和單斜相氧化鋯(m-ZrO_2)組成。還原后復(fù)合粉體主要由立方相鎢(c-W)和單斜相氧化鋯(m-ZrO_2)構(gòu)成。隨著ZrO_2摻雜量的增加,鎢合金粉體粒徑逐漸減小。采用共沸蒸餾法同樣能夠制備出顆粒細小,分布均勻的ZrO_2摻雜鎢合金粉末。水熱法與共沸蒸餾法制備出的粉體形貌相同,粒徑有微小差異,均為亞微米級顆粒。因共沸蒸餾法易于批量化制備,本文采用共沸蒸餾法制備粉體進行后續(xù)燒結(jié)加工。經(jīng)過垂熔燒結(jié)得到的燒結(jié)態(tài)鎢合金,ZrO_2顆粒在基體上彌散分布,顆粒尺寸~1.2μm。氧化鋯在燒結(jié)過程中發(fā)生m-ZrO_2→c-ZrO_2的晶型轉(zhuǎn)變,冷卻至常溫后,其仍然為立方相。添加穩(wěn)定劑Y_2O_3可以在常溫時將ZrO_2穩(wěn)定成立方晶型。燒結(jié)態(tài)鎢合金晶粒尺寸約為25.0μm,旋鍛使晶粒得到細化,晶粒尺寸為15.0μm。經(jīng)過高溫退火,晶粒發(fā)生長大至40.0μm~80.0μm。不同狀態(tài)下鎢合金的晶粒尺寸均隨著氧化鋯摻雜量的增加而減小,這是由于分布于基體晶界處的ZrO_2顆粒能夠抑制晶粒向外擴散生長,起到細化晶粒的作用。隨著氧化鋯摻雜量的增加,鎢合金致密度和硬度也在不斷提高。這是因為摻雜ZrO_2能夠細化晶粒,進而提高其致密度和硬度。經(jīng)過旋鍛加工,燒結(jié)態(tài)中缺陷可以得到改善,所以其硬度有所上升。經(jīng)過高溫退火后,發(fā)生再結(jié)晶,導(dǎo)致晶粒不斷長大,所以降低了其硬度。隨著氧化鋯摻雜量的增加,鎢合金的抗壓強度不斷升高。高溫退火后,由于晶粒重新長大,抗壓強度下降。通過SEM觀察ZrO_2摻雜鎢合金在室溫下均為脆性斷裂斷口。其斷口形狀隨著氧化鋯摻雜量的不同有所改變。分布于晶界處ZrO_2顆粒的在一定程度上阻礙其沿晶斷裂,提高了其屈服強度。高溫壓縮性能測試中,隨著溫度的不斷升高,氧化鋯摻雜鎢合金棒材和純鎢棒的抗壓強度不斷減小。在1000℃~1200℃之間,Zr O2摻雜鎢合金的抗壓強度均高于純鎢棒;溫度高于1200℃時,純鎢的抗壓強度逐漸高于氧化鋯摻雜鎢合金。這是因為此溫度下,鎢基體與氧化鋯顆粒的界面結(jié)合能力不斷弱化,導(dǎo)致鎢合金整體壓縮性能下降。當(dāng)在溫度一定,高溫壓縮應(yīng)變速率不同的情況下,應(yīng)變速率為1/s時,其真實應(yīng)力明顯高于應(yīng)變速率為0.01/s和0.005/s下的真實應(yīng)力。應(yīng)變速率越高,其抗壓強度就越大,材料的塑性變形能力降低。
[Abstract]:The tungsten alloy is widely used in the fields of national defense, medical treatment, aerospace and the like, and can be used for making products such as hard alloy, casting mold, armour-piercing core, electrolytic contact and electrode. The iron oxide (ZrO _ 2) is a very stable material with very high hardness and melting point, and has excellent thermal property, mechanical property, electrical property and high wear resistance and corrosion resistance, and is widely applied in many fields such as the mechanical sub-industry, the aviation industry and the like. In combination with the excellent properties of ZrO _ 2 and W, the room temperature and high-temperature mechanical properties of the tungsten alloy can be improved, and a new type of ZrO _ 2-doped tungsten alloy material has been developed as an important research. The tungsten oxide-doped tungsten alloy powder is prepared by the method of liquid-liquid doping, that is, by adopting a hydrothermal method and an azeotropic distillation method in combination with a conventional powder metallurgy method, and a tungsten alloy material is prepared through the processes of press molding, vertical fusion sintering, rotary forging and the like. The material composition, phase structure transition, microstructure and microstructure of the alloy during the preparation of the alloy are analyzed, and the properties of the alloy are analyzed. In the preparation of the powder by the hydrothermal method, the pH value and the doping amount of ZrO _ 2 have a significant effect on the morphology and the particle size of the precursor powder. When the pH = 0.5, the particles are the most fine. The doping amount of ZrO _ 2 is increased, and the agglomeration and agglomeration of the precursor powder are easy to occur. The powder is composed of monoclinic tungsten oxide (m-WO3) and monoclinic phase oxide (m-ZrO _ 2). The composite powder is mainly composed of cubic phase tungsten (c-W) and monoclinic phase oxide (m-ZrO _ 2). With the increase of the doping amount of ZrO _ 2, the particle size of the tungsten alloy powder gradually decreases. By adopting the azeotropic distillation method, the ZrO _ 2 doped tungsten alloy powder with fine particles and uniform distribution can be prepared. The morphology of the powder prepared by the hydrothermal method and the azeotropic distillation method is the same, and the particle size is slightly different, and is all the sub-micron grade particles. In this paper, an azeotropic distillation method is used to prepare the powder for subsequent sintering. The crystal form of m-ZrO _ 2-c-ZrO _ 2 in the sintering process of the sintered tungsten alloy and the ZrO _ 2 particles which were obtained by the vertical-melting sintering and the particle size of ~ 1.2. m. The crystal form of m-ZrO _ 2-c-ZrO _ 2 in the sintering process was changed, and it was still the cubic phase after cooling to normal temperature. The addition of the stabilizer Y _ 2O _ 3 can stabilize the ZrO _ 2 at normal temperature. The grain size of the sintered tungsten alloy was about 25.0. m u.m, and the grain size was 15.0um. After high-temperature annealing, the grain size was raised to 40.0. m The ZrO _ 2 particles, which are distributed at the grain boundary of the matrix, can inhibit the growth of the crystal grains from the outside and play a role in refining the crystal grains. With the increase of the doping amount of the tungsten oxide, the density and the hardness of the tungsten alloy are also increasing. This is because the doped ZrO _ 2 can refine the crystal grains and further improve the density and the hardness of the crystal. The defects in the sintered state can be improved through the rotary forging process, and the hardness thereof is increased. After high-temperature annealing, the recrystallization is carried out, resulting in the growth of the grains, and the hardness thereof is reduced. The compressive strength of the tungsten alloy is increasing with the increase of the doping amount of the tungsten oxide. After high-temperature annealing, the compressive strength decreased due to the re-growth of the grains. The fracture of ZrO _ 2 doped tungsten alloy at room temperature was observed by SEM. The fracture shape of which changes with the doping amount of the oxide. The ZrO _ 2 particles, which are distributed at the grain boundary, prevent the grain from breaking along the crystal to a certain extent, and the yield strength thereof is improved. In the high-temperature compression performance test, the compressive strength of the tungsten oxide-doped tungsten alloy bar and the pure tungsten rod decreases with the increase of the temperature. The compressive strength of the Zr _ 2-doped tungsten alloy is higher than that of the pure tungsten rod at the temperature of 1000-1200 DEG C, and the compressive strength of the pure tungsten is gradually higher than that of the tungsten oxide-doped tungsten alloy when the temperature is higher than 1200 DEG C. This is because the interface bonding ability of the tungsten matrix and the tungsten oxide particles is continuously weakened at this temperature, resulting in a decrease in the overall compression performance of the tungsten alloy. When the strain rate is 1/ s, the true stress is obviously higher than the true stress at the strain rate of 0.01/ s and 0.005/ s when the temperature is constant and the high-temperature compressive strain rate is different. The higher the strain rate, the greater the compressive strength and the lower the plastic deformation capacity of the material.
【學(xué)位授予單位】：河南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG146.411
本文編號：2456723
[Abstract]:The tungsten alloy is widely used in the fields of national defense, medical treatment, aerospace and the like, and can be used for making products such as hard alloy, casting mold, armour-piercing core, electrolytic contact and electrode. The iron oxide (ZrO _ 2) is a very stable material with very high hardness and melting point, and has excellent thermal property, mechanical property, electrical property and high wear resistance and corrosion resistance, and is widely applied in many fields such as the mechanical sub-industry, the aviation industry and the like. In combination with the excellent properties of ZrO _ 2 and W, the room temperature and high-temperature mechanical properties of the tungsten alloy can be improved, and a new type of ZrO _ 2-doped tungsten alloy material has been developed as an important research. The tungsten oxide-doped tungsten alloy powder is prepared by the method of liquid-liquid doping, that is, by adopting a hydrothermal method and an azeotropic distillation method in combination with a conventional powder metallurgy method, and a tungsten alloy material is prepared through the processes of press molding, vertical fusion sintering, rotary forging and the like. The material composition, phase structure transition, microstructure and microstructure of the alloy during the preparation of the alloy are analyzed, and the properties of the alloy are analyzed. In the preparation of the powder by the hydrothermal method, the pH value and the doping amount of ZrO _ 2 have a significant effect on the morphology and the particle size of the precursor powder. When the pH = 0.5, the particles are the most fine. The doping amount of ZrO _ 2 is increased, and the agglomeration and agglomeration of the precursor powder are easy to occur. The powder is composed of monoclinic tungsten oxide (m-WO3) and monoclinic phase oxide (m-ZrO _ 2). The composite powder is mainly composed of cubic phase tungsten (c-W) and monoclinic phase oxide (m-ZrO _ 2). With the increase of the doping amount of ZrO _ 2, the particle size of the tungsten alloy powder gradually decreases. By adopting the azeotropic distillation method, the ZrO _ 2 doped tungsten alloy powder with fine particles and uniform distribution can be prepared. The morphology of the powder prepared by the hydrothermal method and the azeotropic distillation method is the same, and the particle size is slightly different, and is all the sub-micron grade particles. In this paper, an azeotropic distillation method is used to prepare the powder for subsequent sintering. The crystal form of m-ZrO _ 2-c-ZrO _ 2 in the sintering process of the sintered tungsten alloy and the ZrO _ 2 particles which were obtained by the vertical-melting sintering and the particle size of ~ 1.2. m. The crystal form of m-ZrO _ 2-c-ZrO _ 2 in the sintering process was changed, and it was still the cubic phase after cooling to normal temperature. The addition of the stabilizer Y _ 2O _ 3 can stabilize the ZrO _ 2 at normal temperature. The grain size of the sintered tungsten alloy was about 25.0. m u.m, and the grain size was 15.0um. After high-temperature annealing, the grain size was raised to 40.0. m The ZrO _ 2 particles, which are distributed at the grain boundary of the matrix, can inhibit the growth of the crystal grains from the outside and play a role in refining the crystal grains. With the increase of the doping amount of the tungsten oxide, the density and the hardness of the tungsten alloy are also increasing. This is because the doped ZrO _ 2 can refine the crystal grains and further improve the density and the hardness of the crystal. The defects in the sintered state can be improved through the rotary forging process, and the hardness thereof is increased. After high-temperature annealing, the recrystallization is carried out, resulting in the growth of the grains, and the hardness thereof is reduced. The compressive strength of the tungsten alloy is increasing with the increase of the doping amount of the tungsten oxide. After high-temperature annealing, the compressive strength decreased due to the re-growth of the grains. The fracture of ZrO _ 2 doped tungsten alloy at room temperature was observed by SEM. The fracture shape of which changes with the doping amount of the oxide. The ZrO _ 2 particles, which are distributed at the grain boundary, prevent the grain from breaking along the crystal to a certain extent, and the yield strength thereof is improved. In the high-temperature compression performance test, the compressive strength of the tungsten oxide-doped tungsten alloy bar and the pure tungsten rod decreases with the increase of the temperature. The compressive strength of the Zr _ 2-doped tungsten alloy is higher than that of the pure tungsten rod at the temperature of 1000-1200 DEG C, and the compressive strength of the pure tungsten is gradually higher than that of the tungsten oxide-doped tungsten alloy when the temperature is higher than 1200 DEG C. This is because the interface bonding ability of the tungsten matrix and the tungsten oxide particles is continuously weakened at this temperature, resulting in a decrease in the overall compression performance of the tungsten alloy. When the strain rate is 1/ s, the true stress is obviously higher than the true stress at the strain rate of 0.01/ s and 0.005/ s when the temperature is constant and the high-temperature compressive strain rate is different. The higher the strain rate, the greater the compressive strength and the lower the plastic deformation capacity of the material.
【學(xué)位授予單位】：河南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG146.411
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