Pt—Rh合金的高温挥发

研究了Pt-7Rh和Pt-Rh-Au合金的高温挥发行为.在1200～1350℃合金按抛物线-直线规律失重,且在高温下抛物线-直线失重规律的转换时间变快.在Pt-Rh合金中增加Rh含量和添加Au增大挥发率.Pt-7Rh-3Au合金的挥发激活能为167kJ/mol;Au降低Pt和Pt-7Rh合金的发挥激活能.还讨论了挥发过程的物理机制.     

PtRh_(13)/Pt热电偶的分度及稳定性试验

PtRh_(13)/Pt热电偶是一种新型热电偶,我国六十年代初开始研制,与PtRh_(10)/Pt热电偶相比,其热电动势较大,灵敏度高,是美、英、日等国广泛使用的一种标准型热电偶。国际电工委员会(IEC)也将PtRh_(13)/Pt热电偶定为七种标准型热电偶中的一种,即R型热电偶。随着我国使用PtRh_(13)/Pt热电偶的数量日增,1979年已制订颁布了工业标准(GB1598—79)。为便于国际间的技术交流和进出口设备的测温配套,近两年来,我国生产的PtRh_(13)/Pt热电偶已逐渐靠近IEC标准。为了考核它的热电动势—温度特性与IEC     

Pt—Rh微细热偶的开发研究

1.概述用Pt-Rh合金微细丝构成的热电偶(以下简称微偶)测温迅速准确可靠,广泛用于钢铁冶金和机械铸造工业的测温、定碳和定氧.复合微偶具有两种或两种以上的功能,美国EN公司最新颖的复合微偶能同时测温、定碳、定氧和取样.国外定氧微偶发展很快,目前产量仅次于测温偶.英国JMM公司Pt-10Rh/Pt,Pt-13Rh/Pt微偶使用温度1500～1600℃,在1500℃下误差±3℃;Pt-30Rh/Pt-6Rh微偶,使用温度1600～1750℃,1600℃下误差±4℃,使用时间均在1min内.     

硝酸工厂铂合金催化网的铂耗

铂耗和氨耗是硝酸生产的主要技术指标。在流动氧气氛模拟条件下,以及800~950℃的硝酸生产实际氨氧化环境中,Pt-Rh二元和Pt-Pd-Rh三元合金及其催化网的失重和铂耗均遵循相同的模式,即ΔW/S=Kt2/3与ΨΣ=K't2/3。工厂实际测定数据表明,在常压氨氧化法生产硝酸过程中,Pt-12Pd-3.5Rh合金催化网的铂耗为0.044 g Pt/t(HNO3),比Pt-4Pd-3.5Rh合金催化网的铂耗(0.061g Pt/t(HNO3))低28%;在中压氨氧化法生产硝酸过程中,Pt-12Pd-3.5Rh合金催化网的铂耗为0.121g Pt/t(HNO3),比Pt-5Rh和Pt-10Rh合金催化网的铂耗(0.15~0.153 g Pt/t(HNO3))低21%,而其氨耗比后者降低3%~7%。研究结果证明,在Pt-Rh合金中添加钯或在Pt-Pd-Rh合金中增加钯含量明显降低催化合金的铂耗。     

Pt-10Rh/Pt热偶在还原性气氛中的应用

在Pt、Pt-10Rh中分别加入Y和第二金属组元M得到了符合GB3772·83标准的新型热电偶。采用溶胶 -凝胶涂敷工艺在热电偶丝上制备了Al2 O3·Y2 O3 涂层。对上述涂层的两种热电偶分别在H2 和CO还原性气氛中进行试验 ,结果表明高温下加Y的热电偶无法避免脆断失效 ,而经涂层的热电偶和新型热电偶可通过还原性气氛中长期稳定性试验 ,克服了脆断失效问题。涂层的热电偶在钢厂实际应用表明 ,其使用寿命为未涂层的热电偶 2倍以上。     

熔铸工艺对铂铑热电偶丝不均匀热电动势的影响

国产铂铑热电偶丝在不均匀热电动势指标上与国外同类产品相比存在一定差距。为了减少铂铑热电偶不均匀热电动势,研究了自然凝固和浇铸快速凝固两种凝固方式下重熔次数对高、中频熔炼法制备的偶丝不均匀热电动势的影响。研究结果表明：两种凝固方式下,增加重熔次数均可以减小高、中频熔炼法制备的偶丝不均匀热电动势;采用浇铸快速凝固方式、适当的重熔次数和中频熔炼法制备的偶丝不均匀热电动势明显减小。     

铂族金属高温固溶强化型合金

讨论了高温固溶强化机制和合金元素对Pt固溶强化效应.介绍了铂族金属和Pt-Rh、Pt-Ir和Pt-Pd-Rh固溶型合金的的高温力学性能.借助不同的强化机制,在Pt-Rh或Pt-Pd-Rh合金中添加少量Ir、Ru、Mo、Au等组元,或微量稀有金属Zr、Hf或稀土金属,可以提高合金的高温强度性质和改善抗蠕变能力.     

工作基准Pt—13Rh／Pt热偶丝研究

1.前言 Pt—13Rh/Pt是国际通用的8种标准型热电偶之一,于1922年投入使用。其热电势值和灵敏度最高,性能与Pt—10Rh/Pt热偶相似。自1922年以来,科技工作者对其广泛研究。1968年由美国4家工厂、英国3家工厂提供偶丝,由美国标准局(NBS)、英国物理研究所(NPL)和加拿大国家研究院(NRC)共同研制它的新分度表。1977年国际电工委员会(IEC)将NBS、NPL和NRC共同研制的新分度表推荐为国际标准     

Pt族金属在加压氰化浸出过程中的行为探讨

对加压氰化浸出过程Pt族金属(Pt,Pd,Rh)行为的研究表明,Pt族金属氰化浸出率的顺序为Pd>Pt>Rh,而相应氰配合物高温下稳定性顺序为Rh≈Pt>Pd浸出过程中的行为规律实际上反映的是表面态Pt族金属的化学反应活性顺序,也即金属的原子态稳定性和金属键强度两种变化规律的综合表现,而Pt族金属氰配合物高温稳定性可以由“重Pt族配合物比相应结构的轻Pt族配合物的热力学稳定性更大,动力学惰性更高”以及金属氰配离子反应活性得到解释。     

The High Temperature Creep Behavior of Dispersion Strengthened Pt5Rh Composite

采用大塑性变形法制备氧化物弥散强化铂铑 (Pt5Rh ODS)复合材料,对材料进行了高温蠕变试验。结果表明,复合材料在高温低应力条件下,表现出的名义应力指数随温度变化较小,名义激活能高于纯Pt和Pt10Rh合金,而且比常规合金材料具有更好的高温蠕变性能。复合材料的高温蠕变性能用晶界反应控制来解释,说明复合材料的蠕变受到扩散蠕变机制控制。复合材料的蠕变断裂行为符合连续蠕变损伤中的内截面损伤模型,蠕变断裂特征为沿晶断裂。     

Thermoelectric signal characteristics and average interfacial temperatures in the machining of metals under geometrically defined conditions

The Herbert/Gottwein dynamic thermocouple method of temperature measurement was applied in order to experimentally evaluate the average interfacial temperatures arising in the external cylindrical turning of aluminium, brass, mild steel and stainless steel using high speed steel cutting tools. A detailed investigation of the EMF signal generated was undertaken for purposes of explanation of the DC and AC components which arise and of the influence of the cutting tool condition on the EMF signal generated. The thermoelectric characteristics of each material in conjunction with HSS were determined by means of the furnace method of calibration. A critical appraisal of each phase associated with the dynamic thermocouple method of cutting temperature measurement is undertaken in this paper and interfacial temperatures under a wide range of machine setting parameters for each workpiece material are presented and discussed.     

铂铑10-铂热电偶丝断裂失效分析

利用电子探针显微分析仪（EPMA）对早期断裂的铂铑10-铂热电偶进行了分析。结果表明，热电偶保护管密封不严，使用时环境气氛与偶丝直接接触，磷杂质污染偶丝并在偶丝晶界上形成富Pt-P脆性相，造成沿晶脆性断裂，引起热电偶失效。     

Zr、Y元素对Pt-10Rh合金性能的影响研究

在Pt-10Rh合金中添加少量的Zr、Y元素,利用真空充氩电弧熔炼方法制备了Pt-10Rh-0.5Zr合金及Pt-10Rh-0.5Zr-0.2Y合金。研究了合金的相结构、室温与高温力学性能以及高温抗氧化性能,观察分析了合金高温氧化及高温断口的形貌组织结构。结果表明,合金形成了由铂铑固溶体基体相与少量的金属间化合物相构成的组织结构;添加少量的Zr、Y元素大幅提高了Pt-10Rh合金的力学性能,同时Y元素还显著改善了Pt-10Rh-0.5Zr合金的高温塑性和抗氧化性能。     

Vapor deposition of platinum alloyed nickel aluminide coatings

Platinum-doped NiAl coatings are widely used to increase the oxidation resistance of superalloys. These coatings are usually synthesized by a solid state reaction-diffusion process conducted at high temperature. It requires the chemical vapor deposition of aluminum on a nickel rich superalloy substrate that has been pre-coated with several microns of electrodeposited platinum. Here, we show that an electron beam directed vapor deposition (EB-DVD) technique can be used to deposit well bonded, structurally and chemically homogeneous NiAlPt bond coats of any composition onto superalloy substrates. The approach utilized a high voltage, rapid scan frequency electron beam to independently heat elemental nickel, aluminum and platinum melt pools to create three closely spaced vapor plumes. These vapor plumes were then entrained in an inert gas jet flow, which mixed and directed them to a substrate. By adjusting the electron beam current applied to each elemental source, homogeneous, dense, Pt alloyed β-phase NiAl coatings could be synthesized at substrate temperatures of 1050 °C. The width of the substrate-coating interdiffusion zone was controlled by the deposition temperature and time.     

The pilot test of Pt-Pd and Pt-Rh feeds extracted and separated with a new sulfoxide extractant

Platinum, palladium and rhodium of the raw feeds extracted and separated with a new sulfoxide extractant （MSO） were studied in the paper. The pilot test results showed that the percentage extractions are more than 99% for platinum and palladium in Pt-Pd feed, and the percentage strippings are 100% and 99.2% with HCl and ammonia, respectively. The ratio of palladium to platinum is 0.0016 in stripping platinum solution, and the ratio of platinum to palladium is 0.0020 in stripping palladium solution. The percentage extraction of platinum is 99% in Pt-Rh feed, and the percentage stripping is 100%. The ratio of rhodium to platinum is 0.0002 in stripping platinum solution. Therefore, platinum, palladium, and rhodium feeds are separated effectively with MSO.     

全光亮镀铑添加剂的研究

为了适应饰品加工市场对高光亮镀铑添加剂国产替代进口的需要,在传统镀铑液配方及工艺的基础上,依据电化学原理,设计了全光亮镀铑添加剂的配方组合及工艺流程,并通过正交试验法对所获镀层的表观进行了评定,初步获得了一种新型全光亮镀铑添加剂.阐述了镀铑添加剂的作用机理,探索了最佳工艺用量.结果表明,采用本添加剂所得工艺配方简单,成本适中,操作方便,无毒无害,便于维护.在一定温度和电流密度条件下,所得镀铑层平整光亮,酷似白金,可作为仿白金装饰性镀层的理想工艺.     

Ultra-high temperature intermetallics for the third millennium

Nickel-base superalloys are hugely successful materials, however they are approaching the limit of their high temperature capability. There is a present and future need for ultra-high temperature alloys which are strong at temperatures at least 200°C above the maximum operating temperature of nickel-base superalloys. We are attempting to design an ultra-high temperature alloy based on platinum. Despite its high cost and density such an alloy might have applications in static components for gas turbines, in rockets, glass manufacture and elsewhere. In order to achieve high-temperature strength we are attempting to mimic a nickel-base superalloy structure but using an f.c.c. platinum matrix strengthened by coherent platinum-base intermetallic particles with the L1₂ structure. Microstructural and phase diagram results are given for the Pt–Zr and Pt–Rh–Zr systems, both of which are shown to exhibit low-misfit f.c.c./L1₂ microstructures.     

EMF Measurements of the Na-Si System

The electromotive force (EMF) of galvanic cells with β-alumina solid electrolyte was measured to determine the phase relations and thermodynamic properties of the Na-Si binary system below 800 °C. Na was added by coulometric titration to cells containing known amounts of silicon. The galvanic cells sealed with Corning 1720 Kovar glass had unpredictable lifetimes, lasting from several days to less than one reading. A new ceramic seal consisting of Na₂O-Al₂O₃ eutectic was developed which allowed high temperature EMF measurements up to 800 °C. The solubility of Si in molten Na was determined to be very limited. Properties of the NaSi and Na₄Si₂₃ compounds were derived from the EMF measurements. Differential thermal analysis (DTA) experiments were carried out to determine the onset temperature of phase changes.     

Activity measurement of gallium in the B2 phase of the CoGa–Sb system by the EMF method with zirconia-based solid electrolyte

Gallium activity in the B2 phase regions of both binary Co–Ga and ternary Co–Ga–Sb systems was measured by EMF method with stabilized zirconia solid electrolyte The temperature range was 1073–1273 K and Sb concentrations were 1, 2 and 3 mol fractions. Ga activity at 1173 and 1273 K increases sharply in Ga rich region and the addition of Sb to the CoGa phase increases Ga activity. Activity change corresponds to the lattice parameter change with Sb addition to the CoGa phase.