渗铝改性离子镀NiCrAlY涂层的高温热腐蚀行为

为了进一步改善离子镀NiCrAlY涂层的抗热腐蚀性能,采用粉末包埋法在离子镀NiCrAlY涂层表面上进行渗铝,研究了涂层渗铝前后在850℃含氯硫酸盐膜下的热腐蚀行为.结果表明:在25%NaCl 75%Na2SO4熔盐中850℃热腐蚀40h时,未渗铝的NiCrAlY涂层生成的是外层以Cr2O3为主的氧化膜,渗铝后的NiCrAlY涂层仅生成一层Al2O3膜;未渗铝的NiCrAlY涂层在腐蚀50h后失去保护作用,而渗铝涂层在腐蚀100h后表面仍形成以Al2O3为主的保护膜.因此,渗铝处理可以明显提高原涂层的抗热腐蚀性能.     

退火处理对离子镀NiCrAlY涂层热腐蚀性能的影响

为了进一步改善离子镀NiCrAlY涂层的抗热腐蚀性能,对NiCrAlY涂层在1050℃进行真空退火2h,研究了涂层退火前后的热腐蚀行为.结果表明,退火处理消除了离子镀NiCrAlY涂层的一些孑L洞,涂层形成了γ/γ' β多相平衡组织,使涂层组织更致密;在25%NaCl 75%Na2SO4(质量分数)盐膜下850℃热腐蚀20h时,未退火的NiCrAlY涂层生成的是外层Cr2O3、内层Al2O3的双层氧化膜,退火后的NiCrAlY涂层仅生成一层Al2O3膜,孕育期增长,在一定程度上提高了抗热腐蚀寿命.     

渗铝镍基高温合金热腐蚀行为研究

采用低压气相渗铝工艺制备铝化物涂层 ,在涂层表面涂敷不同NaCl+Na2 SO4 含量的熔盐进行 90 0℃热腐蚀实验 .结果表明 ,涂层对NaCl含量不敏感 ,这与涂层表面生成Al2 O3 氧化膜有关 .涂层能有效提高合金抗热腐蚀性能 .     

Al-Cr涂层对TC21合金抗氧化和热腐蚀性能的影响

采用双辉等离子表面渗铬和后续多弧离子镀铝处理在TC21合金表面制备Al-Cr涂层;同时研究Al-Cr涂层在850℃下的高温氧化行为和850℃下25%NaCl+75%Na_2SO_4(质量分数)混合盐中的热腐蚀行为。结果表明:Al-Cr复合涂层包括表面富Al沉积层、中间Al-Cr扩散层和内侧Cr-Ti互扩散层。在850℃氧化100 h后,Al-Cr涂层表面生成致密Al_2O_3膜,对基体有很好的保护作用;中间Al-Cr扩散层中Cr元素的存在促进Al的选择性氧化,有利于涂层的后续氧化行为。在850℃混合熔盐中腐蚀100 h后,内部Cr-Ti扩散区仍保持完整,涂层表现出较好的热腐蚀抗力。     

Al/Cr复合涂层对Ti2AlNb合金抗热腐蚀性能的影响

目的改善Ti2AlNb合金在高温腐蚀盐环境中的耐热腐蚀性能。方法在Ti2AlNb合金表面通过双层辉光等离子渗铬及磁控溅射镀铝技术制备Al/Cr复合涂层,分析涂层热腐蚀前后的微观形貌和物相组成,并探究涂覆Na2SO4盐膜的试样在不同温度下(750、850、950℃)的热腐蚀行为。结果Al/Cr复合涂层组织均匀致密,且与基体结合良好,厚度约73μm,由表及里依次由Al沉积层、Al/Cr合金层、Cr沉积层、Cr扩散层四部分组成。经不同温度Na2SO4盐热腐蚀后,Al/Cr复合涂层腐蚀程度均显著小于合金基体。涂层试样经750~850℃Na2SO4盐热腐蚀后质量变化较小,850℃腐蚀增重仅0.525 mg/cm^2,而经历950℃、40 h熔盐热腐蚀后失重达到73.571 mg/cm^2,且试样截面出现剥离、脱落现象,Al/Cr复合涂层抵抗热腐蚀能力减弱。结论具有涂层保护的试样抗热腐蚀性能明显优于合金基体。Al/Cr复合涂层在750~850℃Na2SO4盐环境中具有良好的热腐蚀抗力,而更高温度段(850~950℃)的热腐蚀抗力下降。Al/Cr复合涂层在Na2SO4盐环境中良好的抗热腐蚀性得益于涂层中Al、Cr元素氧化形成以Al2O3、Cr2O3为主的混合氧化膜,有效阻碍外界氧气及腐蚀性介质侵入基体。     

TiAl合金表面搪瓷基复合涂层与多弧离子镀NiCrAlY涂层的抗热腐蚀行为对比研究

以Ti-45Al-2Mn-2Nb合金为基体,采用多弧离子镀制备NiCrAlY涂层、喷涂-烧结法制备搪瓷基复合涂层,对比研究了2种涂层以及合金基体的热腐蚀行为。热腐蚀实验温度为850℃,选用饱和盐溶液溶质成分为75%Na_2SO_4+25%NaCl (质量分数),涂盐量为1.5～2.5 mg/cm~2。研究结果表明,合金基体完全不具备抗热腐蚀能力,表面形成的氧化膜疏松多孔,且极易剥落;NiCrAlY涂层表面生成的保护性Al_2O_3膜提高了合金的抗热腐蚀能力,然而涂层与基体间严重的互扩散及Al_2O_3膜与熔盐的碱性溶解使得NiCrAlY涂层逐渐失效,热腐蚀60 h即出现氧化膜的剥落;而搪瓷基复合涂层在熔盐环境中只发生了轻微的物理溶解,具有极高的热稳定性及较低的热腐蚀速率,有效地阻隔了腐蚀性离子的入侵,抗热腐蚀性能优异。     

三种β-NiAl相材料的短期热腐蚀行为比较研究

在Ni-30Al(mass%,下同)和Ni-20Cr-10Al铸态合金上进行粉末包埋渗铝,分别得到纯β-NiAl相涂层和β-(Ni,Cr)Al相涂层.在这两种渗铝试样和铸态Ni-20Cr-13Al合金(含β-NiAl、γ′-Ni3Al、α-Cr相)上涂覆了硫酸钠薄膜,进行900℃热腐蚀测试.经过10小时热腐蚀测试后,三种试样表面均生成Al2O3膜.腐蚀动力学分析表明,Cr对提高材料的抗热腐蚀性能是有益的;Ni-20Cr-10Al渗铝涂层试样的增重最低,仅为铸态Ni-20Cr-13Al合金试样增重的80%左右,Ni-30Al渗铝涂层试样增重的50%左右.     

K452合金表面CVD渗铝涂层制备温度对其750℃硫酸盐热腐蚀行为的影响

采用化学气相沉积(CVD)技术在K452合金表面沉积渗铝涂层,沉积温度分别为850、950和1050℃。研究了沉积温度对CVD渗铝涂层在750℃空气中表面沉积Na₂SO₄及Na₂SO₄+NaCl环境下热腐蚀行为的影响。采用扫描电子显微镜(SEM)、X射线能谱仪(EDS)和X射线衍射仪(XRD)对腐蚀前和后的试样进行截面形貌观察和物相结构分析。结果表明,在750℃下表面沉积Na₂SO₄及Na₂SO₄+NaCl热腐蚀50 h后,3种涂层试样均表现出了较K452合金更好的抗热腐蚀性能,且涂层的抗热腐蚀性能随着涂层沉积温度的增加而增强。     

DD98M纳米晶AlSi渗层制备及抗高温腐蚀性能研究

采用磁控溅射技术在DD98M合金表面制备了同成份的纳米晶,采用多弧离子镀技术在DD98M纳米晶涂层表面沉积了AlSi涂层,对上述制备态纳米晶+AlSi复合涂层进行了真空扩散处理,得到了外层为β-NiAl层、内层为γ'-Ni_3Al层的双层结构复合涂层。研究了合金、DD98M纳米晶涂层及复合涂层在1050℃恒温氧化及900℃下Na_2SO_4+25%K_2SO_4混合熔盐体系中的热腐蚀行为。结果表明:1050℃恒温氧化时,DD98M合金表面生成NiO,α-Al_2O_3,Ta_(0.8)O_2,CrTaO_4及NiAl_2O_4等组成的混合氧化物膜,氧化膜开裂剥落严重。纳米晶涂层表面生成α-Al_2O_3和少量NiAl_2O_4组成的混合氧化物膜,复合涂层表面形成了均匀致密的单一α-Al_2O_3膜。纳米晶涂层和复合涂层大幅提高了合金的抗恒温氧化性能。在900℃下Na_2SO_4+25%K_2SO_4熔盐中,DD98M合金20 h后即发生了灾难性腐蚀,沉积态纳米晶及其预氧化涂层提高了合金的抗热腐蚀性能,复合涂层大幅提高了合金的抗热腐蚀性能。     

电弧离子镀NiCrAlY涂层对镍基单晶合金热腐蚀行为的影响

采用电弧离子镀技术在镍基单晶合金表面沉积Ni28Cr11Al0.5Y涂层,研究镍基单晶合金及其Ni28Cr11Al0.5Y涂层在900℃的75%Na2SO4+25%K2SO4(质量分数)熔盐中的热腐蚀行为。结果表明:镍基单晶合金受到了严重的热腐蚀,镍基单晶合金内部出现了严重的内硫化和内氧化现象,且内硫化物区域和内氧化物区域出现明显分层结构,与外腐蚀层相邻的区域为内氧化区域,远离外腐蚀层的基体内部形成内硫化区域;而Ni28Cr11Al0.5Y涂层在热腐蚀过程中,表面生成连续的Al2O3氧化膜,且随腐蚀时间延长,Al2O3氧化膜的厚度增大,表现出优良的抗热腐蚀性能。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.