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At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Vacuum Plasma Spray of CuCrNb Alloy for Advanced Liquid - Fuel Combustion Chambers

The copper-8 atomic percent chromium-4 atomic percent niobium (CuCrNb) alloy was developed by Glenn Research Center (formally Lewis Research Center) as an improved alloy for combustion chamber liners. In comparison to NARloy-Z, the baseline (as in Space Shuttle Main Engine) alloy for such liners, CuCrNb demonstrates mechanical and thermophysical properties equivalent to NARloy-Z, but at temperatures 100 C to 150 C (180 F to 270 F) higher. Anticipated materials related benefits include decreasing the thrust cell liner weight 5% to 20%, increasing the service life at least two fold over current combustion chamber design, and increasing the safety margins available to designers. By adding an oxidation and thermal barrier coating to the liner, the combustion chamber can operate at even higher temperatures. For all these benefits, however, this alloy cannot be formed using conventional casting and forging methods because of the levels of chromium and niobium, which exceed their solubility limit in copper. Until recently, the only forming process that maintains the required microstructure of CrNb intermetallics is powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. Vacuum plasma spray (VPS) has been demonstrated as a method to form structural articles including small combustion chambers from the CuCrNb alloy. In addition, an oxidation and thermal barrier layer can be formed integrally on the hot wall of the liner that improve performance and extend service life. This paper discusses the metallurgy and thermomechanical properties of VPS formed CuCrNb versus the baseline powder metallurgy process, and the manufacturing of small combustion chamber liners at Marshall Space Flight Center using the VPS process. The benefits to advanced propulsion initiatives of using VPS to fabricate combustion chamber liners while maintaining the superior CuCrNb properties are also presented.

Zimmerman, Frank↗
NASA NTRS2000

Polymer-Oxygen Compatibility Testing: Effect of Oxygen Aging on Ignition and Combustion Properties

The oxygen compatibility of six polymers used in oxygen service was evaluated after exposure for 48 hours to oxygen pressures ranging from 350 to 6200 kPa (50 to 900 psia), and temperatures ranging from 50 to 250 C (122 to 302 F). Three elastomers were tested: CR rubber (C873-70), FKM fluorocarbon rubber (Viton A), and MPQ silicone rubber (MIL-ZZ-765, Class 2); and three thermoplastics were tested: polyhexamethylene adipamide (Zytel 42), polytetrafluoroethylene (Teflon TFE), and polychlorotrifluoroethylene (Neoflon CTFE M400H). Post-aging changes in mass, dimensions, tensile strength, elongation at break, and durometer hardness were determined. Also, the compression set was determined for the three elastomers. Results show that the properties under investigation were more sensitive to oxygen pressure at low to moderate temperatures, and more sensitive to temperature at low to moderate oxygen pressures. Inspection of the results also suggested that both chain scissioning and cross-linking processes were operative, consistent with heterogeneous oxidation. Attempts are underway to verify conclusively the occurrence of heterogeneous oxidation using a simple modulus profiling technique. Finally, the effect of aging at 620 kpa (90 psia) and 121 C (250 F) on ignition and combustion resistance was determined. As expected, aged polymers were less ignitable and combustible (had higher AlTs and lower heats of combustion). Special attention was given to Neoflon CTFE. More specifically, the effect of process history (compression versus extrusion molding) and percent crystallinity (quick- versus slow-quenched) on the AIT, heat of combustion, and impact sensitivity of Neoflon CTFE was investigated. Results show the AIT, heat of combustion, and impact sensitivity to be essentially independent of Neoflon CTFE process history and structure.

Waller, Jess M.↗
NASA NTRS2000

Flow in the Proximity of the Pin-Tool in Friction Stir Welding and Its Relation to Weld Homogeneity

In the Friction Stir Welding (FSW) process a rotating pin inserted into a seam literally stirs the metal from each side of the seam together. It is proposed that the flow in the vicinity of the pin-tool comprises a primary rapid shear over a cylindrical envelope covering the pin-tool and a relatively slow secondary flow taking the form of a ring vortex about the tool circumference. This model is consistent with a plastic characterization of metal flow, where discontinuities in shear flow are allowed but not viscous effects. It is consistent with experiments employing several different kinds of tracer: atomic markers, shot, and wire. If a rotating disc with angular velocity w is superposed on a translating continuum with linear velocity omega, the trajectories of tracer points become circular arcs centered upon a point displaced laterally a distance v/omega from the center of rotation of the disc in the direction of the advancing side of the disc. In the present model a stream of metal approaching the tool (taken as the coordinate system of observation) is sheared at the slip surface, rapidly rotated around the tool, sheared again on the opposite side of the tool, and deposited in the wake of the tool. Local shearing rates are high, comparable to metal cutting in this model. The flow patterns in the vicinity of the pin-tool determine the level of homogenization and dispersal of contaminants that occurs in the FSW process. The approaching metal streams enfold one another as they are rotated around the tool. Neglecting mixing they return to the same lateral position in the wake of the tool preserving lateral tracer positions as if the metal had flowed past the tool like an extrusion instead of being rotated around it. (The seam is, however, obliterated.) The metal stream of thickness approximately that of the tool diameter D is wiped past the tool at elevated temperatures drawn out to a thickness of v/2(omega) in the wiping zone. Mixing distances in the wiping zone are multiplied in the unfolded metal. Inhomogeneities on a smaller scale than the mixing length are obliterated, but structure on a larger scale may be transmitted to the wake of a FSW weld.

Nunes, Arthur C., Jr.↗
NASA NTRS1999

Vibration-Induced Droplet Atomization

Thermal management is critical to a number of technologies used in a microgravity environment and in Earth-based systems. Examples include electronic cooling, power generation systems, metal forming and extrusion, and HVAC (heating, venting, and air conditioning) systems. One technique that can deliver the large heat fluxes required for many of these technologies is two-phase heat transfer. This type of heat transfer is seen in the boiling or evaporation of a liquid and in the condensation of a vapor. Such processes provide very large heat fluxes with small temperature differences. Our research program is directed toward the development of a new, two-phase heat transfer cell for use in a microgravity environment. In this paper, we consider the main technology used in this cell, a novel technique for the atomization of a liquid called vibration-induced droplet atomization. In this process, a small liquid droplet is placed on a thin metal diaphragm that is made to vibrate by an attached piezoelectric transducer. The vibration induces capillary waves on the free surface of the droplet that grow in amplitude and then begin to eject small secondary droplets from the wave crests. In some situations, this ejection process develops so rapidly that the entire droplet seems to burst into a small cloud of atomized droplets that move away from the diaphragm at speeds of up to 50 cm/s. By incorporating this process into a heat transfer cell, the active atomization and transport of the small liquid droplets could provide a large heat flux capability for the device. Experimental results are presented that document the behavior of the diaphragm and the droplet during the course of a typical bursting event. In addition, a simple mathematical model is presented that qualitatively reproduces all of the essential features we have seen in a burst event. From these two investigations, we have shown that delayed droplet bursting results when the system passes through a resonance condition. This occurs when the initial acceleration of the diaphragm is higher than the critical acceleration and the driving frequency is larger than the initial resonance frequency of the diaphragm-droplet system. We have incorporated this droplet atomization device into a design for a new heat transfer cell for use in a microgravity environment. The cell is essentially a cylindrical container with a hot surface on one end and a cold surface on the other. The vibrating diaphragm is mounted in the center of the cold surface. Heat transfer occurs through droplet evaporation and condensation on the hot and cold ends of the cell. A prototype of this heat transfer cell has been built and tested. It can operate continuously and provides a modest level of heat transfer, about 20 W/sq cm. Our work during the next few years will be to optimize the design of this cell to see if we can produce a device that has significantly better performance than conventional heat exchangers and heat pipes.

Smith, M. K.↗
NASA NTRS2001

Solid Free-Form Fabrication of Continuous Fiber Reinforced Composites for Propulsion Application

For propulsion related applications, materials must be able to demonstrate excellent ablation and oxidation resistance at temperature approaching 3500 C, adequate load bearing capabilities, non-catastrophic failure modes, and ability to withstand transient thermal shock. A potential list of propulsion-material property requirements includes, low density, high elastic modulus, low thermal-expansion coefficient, high thermal conductivity, excellent erosion and oxidation/corrosion resistance, and flaw-insensitivity. In many cases, they will also need to be able to be joined, survive thermal cycling and multi-axial stress states, and for reusable applications, the materials must maintain the above attributes after prolonged exposure to extremely harsh chemical environments. The final and possibly most important attribute for these materials are the need to be lower cost and readily available in large quantities. Recently, Advanced Ceramics Research, Inc. (ACR) has developed low cost, flexible-manufacturing processes for Zr & Hf-based carbon fiber reinforced composites, materials with good oxidation and ablation resistance up to 3500 C. This process, called Continuous Composite Co-extrusion (C(sup 3)), incorporates carbon fibers to fabricate 'in-situ' carbide and boride-matrix/carbon fiber composites. M is a variation of ACR's manufacturing process for low-cost structural ceramic materials called Fibrous Monoliths with carbon fiber reinforcements. Fibrous Monolithic materials have a distinct fibrous texture, consist of intertwined cells of a primary phase, separated by cell boundaries of a tailored secondary phase and show very high fracture energies, damage tolerance, and graceful failure. Since they are monolithic powder based composites; they can be manufactured by conventional powder processing techniques using inexpensive raw materials. This combination of high performance and low cost is a breakthrough that could enable wider application of ceramics in high temperature applications. Typical volume fractions of the two phases are 80 to 95% for the cell phase and 5 to 20% for the interpenetrating cell boundary phase. ACR is currently developing an innovative solid freeform form fabrication (SFF) approach to produce Hf and Zr based ceramic composite components reinforced with continuous carbon fiber tows for critical structural components such as tubes and blisks. The process is simple, robust and will be widely applicable to a number of material systems. This technique was originally developed at the University of Delaware Center for Composite Materials (UD-CCM) for rapid fabrication of polymer matrix composites by a technique called automated tow placement or ATP. The current process is being developed in collaboration with UD-CCM. The paper will detail the freeform fabrication process to create low-cost ceramic fiber reinforced composites for high-temperature applications. The results of mechanical properties and microstructural characterization will be presented, together with examples of complex shapes and parts. It is believed that the process will be able to create complex shaped parts for propulsion applications at an order of magnitude lower cost than current CVI and PIP processes.

Vaidyanathan, R.↗
NASA NTRS2001

Vacuum Plasma Spray of Cu-8Cr-4Nb for Advanced Liquid-Fuel Combustion Chambers

Vacuum plasma spray (VPS) formed Cu-8Cr-4Nb alloy, with low oxygen, exhibits higher strength at room and elevated temperature than material formed by extrusion. The VPS formed material exhibits slightly lower ductility than the extruded material. VPS forming of Cu-8Cr-4Nb can be used to produce near net structures with mechanical properties comparable to current extruded material.

Zimmerman, F.↗
NASA NTRS2000

Nutritional Evaluation of NASA's Rodent Food Bar Diet

Tests are being conducted on NASA's rodent Food Bar in preparation for long-term use as the rat and mouse diet aboard the International Space Station. Nutritional analyses are performed after the bars are manufactured and then repeated periodically to determine nutritional stability. The primary factors analyzed are protein, ash, fat, fiber, moisture, amino acids, fatty acids, and minerals. Nutrient levels are compared to values published in the National Research Council's dietary requirements for rodents, and also to those contained in several commonly used commercial rodent lab diets. The Food Bar is manufactured from a powdered diet to which moisture is added as it is processed through an extruder. The bars are dipped into potassium sorbate, vacuum-sealed, and irradiated. In order to determine nutrient changes during extrusion and irradiation, the powdered diet, the non-irradiated bars, and the irradiated bars are all analyzed. We have observed lower values for some nutrients (iodine, vitamin K, and iron) in the Food Bars compared with NRC requirements. Many nutrients in the Food Bars are contained at a higher level than levels in the NRC requirements. An additional factor we are investigating is the 26% moisture level in the Food Bars, which drops to about 15% within a week, compared to a stable 10% moisture in many standard lab chow diets. In addition to the nutritional analyses, the food bar is being fed to several strains of rats and mice, and feeding study and necropsy results are being observed (Barrett et al, unpublished data). Information from the nutritional analyses and from the rodent studies will enable us to recommend the formulation that will most adequately meet the rodent Food Bar requirements for long-term use aboard the Space Station.

Barrett, Joyce E.↗
NASA NTRS1999

Flow Trajectories in Friction Stir Welding

In the Friction Stir Welding (FSW) process, a rotating, shouldered tool with a threaded pin is inserted under pressure along the seam of two pieces of metal which are tightly clamped together, and secured against a rigid anvil underneath. The rotating pin travels along the seam and through a combination of pressure and friction heating produces a zone of plastic deformation around the pin within the workpiece on either side of the seam. As the pin is moved in the direction of welding, the plasticised material moves around the tool and bonds together behind it. The elements of the material flow behavior are a combination of three elements. There is a rotational transport of material being carried around the tool, extrusion of material being forced around the pin on both sides into the cavity created behind it, and a lifting and dropping of material as it is stirred and mixed by the rotating action of the pin. It was assumed that rotational motion of the plastic zone is the primary mechanism for transport of material around the welding tool. A kinematic mathematical model was used to compute trajectories of material movement for various distributions of rotational slip within the plastic zone. These trajectories were then compared with the results of an experiment that produced radiographs of markers embedded in a workpiece that was welded with the FSW process. It was assumed that the copper wire markers retained their original length as the aluminum material flowed around them. The kinematic model included a constraint so that the displacements were such that the total length of the wire markers did not increase after deformation. There was good agreement between the calculated trajectories for the case of localized slip at the outer surface of the plastic deformation zone and the radiographs of the copper wire markers. The trajectories differed markedly from the radiograph traces when a distributed slip zone was assumed. It was concluded that the flow field could be described generally by a rotating plug model with slip occurring on the surface at the outer boundary of the plastic zone.

Bernstein, Edward L.↗
NASA NTRS1998

Prototyping the Future

Advanced Ceramics Research (ACR) of Tucson, Arizona, researches transforming scientific concepts into technological achievement. Through the SBIR (Small Business Innovative Research) program, ACR developed a high pressure and temperature fused deposition system, a prototyping system that is known as extrusion freeform fabrication. This system is useful in manufacturing prosthetics. ACR also developed a three-dimensional rapid prototyping process in which physical models are quickly created directly from computer generated models. Marshall Space Flight Center also contracted ACR to fabricate a set of ceramic engines to be appraised for a solar thermal rocket engine test program.

Source record↗
NASA NTRS2002

Investigation of Friction Stir Welding and Laser Engineered Net Shaping of Metal Matrix Composite Materials

The improvement in weld quality by the friction stir welding (FSW) process invented by TWI of Cambridge, England, patented in 1991, has prompted investigation of this process for advanced structural materials including Al metal matrix composite (Al-MMC) materials. Such materials can have high specific stiffness and other potential beneficial properties for the extreme environments in space. Developments of discontinuous reinforced Al-MMCs have found potential space applications and the future for such applications is quite promising. The space industry has recognized advantages of the FSW process over conventional welding processes such as the absence of a melt zone, reduced distortion, elimination of the need for shielding gases, and ease of automation. The process has been well proven for aluminum alloys, and work is being carried out for ferrous materials, magnesium alloys and copper alloys. Development work in the FSW welding process for joining of Al-MMCs is relatively recent and some of this and related work can be found in referenced research publications. NASA engineers have undertaken to spear head this research development work for FSW process investigation of Al-MMCs. Some of the reported related work has pointed out the difficulty in fusion welding of particulate reinforced MMCs where liquid Al will react with SiC to precipitate aluminum carbide (Al4C3). Advantages of no such reaction and no need for joint preparation for the FSW process is anticipated in the welding of Al-MMCs. The FSW process has been best described as a combination of extrusion and forging of metals. This is carried out as the pin tool rotates and is slowly plunged into the bond line of the joint as the pin tool's shoulder is in intimate contact with the work piece. The material is friction-stirred into a quality weld.

Ravinder M. Diwan↗
NASA NTRS2001

Aerospace Structural Materials Handbook Supplement GRCop-84

GRCop-84 is a high strength-high conductivity copper-based alloy developed at NASA Glenn Research Center for combustion chamber liners of regeneratively cooled rocket engines. It also has promise for other high heat flux applications operating at temperatures up to 700 C (1292 F) and potentially higher. The alloy must be made by powder metallurgy techniques such as gas atomization. Slower cooling rates such as those experienced during casting do not develop a proper microstructure. Once made into powder, the alloy exhibits excellent processability using conventional consolidation and forming techniques, e.g., extrusion and rolling. GRCop-84 is strengthened by a combination of dispersion and precipitation strengthening by fine (50-500 nanometer (2-20 microinch)) Cr2Nb particles and Hall-Petch strengthening from a fine copper grain size. The presence of a high volume fraction of particles prevents grain boundary sliding at high temperatures and contributes to the alloy's overall good high temperature mechanical properties. Maximum thermal conductivity is obtained by using two alloying elements (Cr, Nb) with limited solubility in solid Cu that form a high temperature intermetallic compound with an even lower solid solubility. The resulting matrix of the alloy is nearly pure copper. The limited solubility also minimizes Cr2Nb particle coarsening at elevated temperatures and enhances microstructural and mechanical property stability. Further enhancement of the microstructural stability is obtained by using a high volume fraction (approx. 14 vol.%) of Cr2Nb particles that effectively pin grain growth.

Ellis, David L.↗
NASA NTRS2002

The Cryogenic Tensile Properties of an Extruded Aluminum-Beryllium Alloy

Basic mechanical properties; i.e., ultimate tensile strength, yield strength, percent elongation, and elastic modulus, were obtained for the aluminum-beryllium alloy, AlBeMet162, at cryogenic (-195.5 C (-320 F) and -252.8 C (-423 F)) temperatures. The material evaluated was purchased to the requirements of SAE-AMS7912, "Aluminum-Beryllium Alloy, Extrusions."

Gamwell, W. R.↗
NASA NTRS2002

A Review of Single Source Precursors for the Deposition of Ternary Chalcopyrite Materials

The development of thin-film solar cells on flexible, lightweight, space-qualified durable substrates (i.e. Kapton) provides an attractive solution to fabricating solar arrays with high specific power, (W/kg). The syntheses and thermal modulation of ternary single source precursors, based on the [{LR}2Cu(SR')2In(SR')2] architecture in good yields are described. Thermogravimetric analyses (TGA) and Low temperature Differential Scanning Caloriometry, (DSC) demonstrate that controlled manipulation of the steric and electronic properties of either the group five-donor and/or chalcogenide moiety permits directed adjustment of the thermal stability and physical properties of the precursors. TGA-Evolved Gas Analysis, confirms that single precursors decompose by the initial extrusion of the sulphide moiety, followed by the loss of the neutral donor group, (L) to release the ternary chalcopyrite matrix. X-ray diffraction studies, EDS and SEM on the non-volatile pyrolized material demonstrate that these derivatives afford single-phase CuInS2/CuInSe2 materials at low temperature. Thin-film fabrication studies demonstrate that these single source precursors can be used in a spray chemical vapor deposition process, for depositing CuInS2 onto flexible polymer substrates at temperatures less than 400 C.

Banger, K. K.↗
NASA NTRS2002

Geology and Origin of Europa's Mitten Feature (Murias Chaos)

The "Mitten" (provisionally named Murias Chaos by the International Astronomical Union) is a region of elevated chaos-like terrain in the leading hemisphere of Europa. Its origin had been explained under the currently debated theories of melting through a thin lithosphere or convection within a thick one. Galileo observations reveal several characteristics that suggest that the Mitten is distinct from typical chaos terrain and point to a different formational process. Photoclinometric elevation estimates suggest that the Mitten is slightly elevated with respect to the surrounding terrain; geologic relations indicate that it must have raised significantly from the plains in its past, resembling disrupted domes on Europa's trailing hemisphere. Moreover, the Mitten material appears to have extruded onto the plains and flowed for tens of kilometers. The area subsequently subsided as a result of isostatic adjustment, viscous relaxation, and/or plains loading. Using plate flexure models, we estimated the elastic lithosphere in the area to be several kilometers thick. We propose that the Mitten originated by the ascent and extrusion of a large thermal diapir. Thermal-mechanical modeling shows that a Mitten-sized plume would remain sufficiently warm and buoyant to pierce through the crust and flow unconfined on the surface. Such a diapir probably had an initial radius between 5 and 8 km and an initial depth of 20-40 km, consistent with a thick-lithosphere model. In this scenario the Mitten appears to represent the surface expression of the rare ascent of a large diapir, in contrast to lenticulae and chaos terrain, which may form by isolated and clustered small diapirs, respectively.

Figueredo, P. H.↗
NASA NTRS2003

Development of a Novel Discontinuously Reinforced Aluminum for Space Applications

The present results indicated that: Al-Sc-Mg-X alloys were selected to provide higher strength from -423 to 450F. SiC and B4C were chosen as reinforcements. Fine spherical powder of Al-Sc-Mg-X was produced using helium gas atomization. Matrix alloy and DRA were processed using vacuum hot processing and extrusion. DRA showed very high strength 100ksi at cryo, RT and hydrogen. Ductility was low. Matrix alloy exhibited high strength and ductility. LCF of matrix was higher than DRA in high strain range.

Pandey, Awadh↗
NASA NTRS2003

Cryogenic Properties of Aluminum Beryllium and Beryllium Materials

Ultimate tensile strength, yield strength, and elongation were obtained for the aluminum-beryllium alloy, AlBeMetl62 (38%Al-62%Be), at cryogenic (-195.5 C (-320 F) and (-252.8 C) (-423 F)) temperatures, and for an optical grade beryllium, O-30H (99%Be), at -252.8 C. AlBeMetl62 material was purchased to the requirements of SAE-AMS7912, "Aluminum-Beryllium Alloy, Extrusions." O-30H material was purchased to the requirements of Brush Wellman Inc. specification O-30H Optical Grade Beryllium. The ultimate tensile and yield strengths for extruded AlBeMetl62 material increased with decreasing temperature, and the percent elongation decreased with decreasing temperature. Design properties for the ultimate tensile strength, yield strength, and percent elongation for extruded AlBeMetl62 were generated. It was not possible to distinguish a difference in the room and cryogenic ultimate strength for the hot isostatically pressed (HIP'ed) O-30H material. The O30H elongation decreased with decreasing temperature.

Gamwell, Wayne R.↗
NASA NTRS2003

Grooved Terrain on Ganymede: A Galileo-based Synthesis

Swaths of bright "grooved terrain" (sulci) on Ganymede are 10s to 100s of kilometers wide and cross-cut the older dark terrain, forming an intricate patchwork across 2/3 of Ganymede's surface. The view of grooved terrain developed from Voyager images is that bright cells are broad graben infilled by extrusion of relatively clean (silicate-poor) liquid water, warm ice, or icy slush, and then extended and faulted. Galileo imaging has greatly improved understanding of the emplacement history and geological implications of grooved terrain, supporting a rift-like model for its formation.

Pappalardo, Robert T.↗
NASA NTRS2003

Fe-Ti-Cr-Oxides in Martian Meteorite EETA79001 Studied by Point-counting Procedure Using Raman Spectroscopy

Fe-Ti-Cr-Oxide minerals contain much information about rock petrogenesis and alteration. Among the most important in the petrology of common intrusive and extrusive rocks are those of the FeO-TiO2-Cr2O3 compositional system chromite, ulv spinel-magnetite, and ilmenite-hematite. These minerals retain memories of oxygen fugacity. Their exsolution into companion mineral pairs give constraints on formation temperature and cooling rate. Laser Raman spectroscopy is anticipated to be a powerful technique for characterization of materials on the surface of Mars. A Mars Microbeam Raman Spectrometer (MMRS) is under development. It combines a micro sized laser beam and an automatic point-counting mechanism, and so can detect minor minerals or weak Raman-scattering phases such as Fe- Ti-Cr-oxides in mixtures (rocks & soils), and provide information on grain size and mineral mode. Most Fe-Ti-Cr-oxides produce weaker Raman signals than those from oxyanionic minerals, e.g. carbonates, sulfates, phosphates, and silicates, partly because most of them are intrinsically weaker Raman scatters, and partly because their dark colors limit the penetration depth of the excitation laser beam (visible wavelength) and of the Raman radiation produced. The purpose of this study is to show how well the Fe-Ti-Cr-oxides can be characterized by on-surface planetary exploration using Raman spectroscopy. We studied the basic Raman features of common examples of these minerals using well-characterized individual mineral grains. The knowledge gained was then used to study the Fe-Ti-Cr-oxides in Martian meteorite EETA79001, especially effects of compositional and structural variations on their Raman features.

Wang, Alian↗