As the third generation of rare earth permanent magnet material, sintered Nd-Fe-B permanent magnets have been widely used in many application fields due to their excellent magnetic properties[1]. However, for traditional Nd-Fe-B magnets, the less abundant elements Nd and Pr have been excessive consumed, while the utilization rate of the most abundant elements La and Ce is very low due to the significantly magnetic properties deterioration of (Nd,Ce/La)-Fe-B magnets by doping the Ce or La directly. Recent studies found that one kind of preparation technology can effectively reduces the deterioration of magnetic properties resulting from the addition of rare earth La and Ce[2-4]. As known, sintering and annealing processes play an important role …show more content…
Two typed as-sintered magnets without annealing process were prepared by Single-main-phase and Dual-main-phase methods, which were reported in previous study[5]. The microstructure of (Ce,Nd)-Fe-B based as-sintered magnets were studied by scanning electron microscope(SEM). The demagnetization curves of magnets at different temperature were measured using a NIM-500C hysteresigraph …show more content…
At the same time, Type II as-sintered magnet exhibits better squareness than that of Type I as-sintered magnet. The microstructures of the two typed magnets were shown in Fig.1. It was found that the microstructure of Type II magnet is superior to that of Type I magnet. On the other hand, Type II magnet exhibits better wettability between main phase and grain-boundary phase than that of Type I magnet. The RE-rich phases of Type II magnet have more continuous and uniform distribution (red regions in Fig.1 (b)). In contrast, this kind of situation is rarely appear in Type I magnet. It is precisely because of the optimization of grain-boundary, the magnetic properties of Type II magnet were improved slightly. The room temperature and elevated temperature demagnetization curves of the two typed magnets were shown in Fig.2. The remanence (Br), coercivity (Hcj) and maximum energy product (BH)max are all decrease with the increase of temperature. The temperature coefficients of remanence (α) and coercivity (β) usually represent thermal stability. The absolute value of β (from 20°C to 120 °C) for Type II magnet (|β|=0.665%/°C) is lower than that of Type I magnet (|β|=0.685%/°C), which indicates the thermal stability improved
Gadolinium and its performance were limited by the use of passive regenerators and heat exchangers in the refrigeration cycle [25]. So, a magnetic refrigeration device must utilize a regenerative process to produce a large enough temperature span to be useful for refrigeration purposes [26].
being picked up by the nail. The strength of an electromagnet can also be altered by varying the current or voltage. The more induced voltage, the stronger the electromagnet. An alternative way to strengthen an electromagnet is to replace the core with a "soft" iron. core. The.. Prediction: -.
Magnetism is very useful in our daily life. A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. In addition, magnetic field is a region which a magnetic material experiences a force as the result of the presence of a magnet or a current carrying conductor. Current carrying conductors also known as wire. As we know there have north pole and south pole of a magnet. If same pole of magnet approaches each other, there will repel each other. In contrast, if different pole of magnet approaches each other, they will attract. These are same with the electric charge, if same charge it will repel, different charge it will attract. Although magnets and magnetism were known much earlier, the study of magnetic fields began in 1269 when French scholar Petrus Peregrinus de Maricourt mapped out the magnetic field on the surface of a spherical magnet using iron needles [search from Wikipedia]. Noting that the resulting field lines crossed at two points he named those points 'poles' in analogy to Earth's poles. Each magnet has its own magnetic field which experiences a force as the result of the presence of a magnet and magnetic field has made up of magnetic field lines. The properties of magnetic field lines is it begin at the north pole and end at the south pole. The north pole always flow out while south pole always flow in. The closer the magnetic field lines, the strength of magnetic field increases. Furthermore, these line cannot cross each other. Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets. Ferromagnetic materials...
To achieve the best possible way to heat up your meals, the microwave does not use solid state devices. Instead, electron beams from tubes under the combined effect of the electric and magnetic fields that are made to curve and follow trajectories. Magnetrons are also mostly used in microwave ovens and it has changed everything. In 1921 it was first discovered and put into use and as the years continue...
Aim To investigate what affects temperature has on the strength of a magnet. Hypothesis: My hypothesis is that as the temperature of the magnet increases the strength of the magnet will decrease. This is because of the atomic structure of the elements that make up the alloy.
Force Field Analysis is a method for listing, discussing, and assessing the various forces for and against a proposed change. A force field analysis helps analyzing all of the Things that will impact change to what you are trying to do, and it gives you the pros and cons of the situation. Having identified these, you can then develop strategies to reduce the impact of the opposing forces and strengthen the supporting forces. An effective team building tool, it is especially useful when you want to overcome resistance to change(Lewin K 1997). , The life space includes only those aspects of the environment that are perceived at some level, either consciously or unconsciously, by the individual (M. Lewin 1998) because Wheeler (2008, p. 1640) observed that: ‘[the] Life space is the total psychological environment that the person experiences subjectively, although not necessarily consciously’, Therefore, in order to understand, predict and begin to change a person’s behaviour, it is necessary to take into account everything about the person and his/her perceptual or psychological environment in order to construct the person’s life space (Lewin 1943a).
A magnet can be made from different materials, but loadstone is the natural form. The most important part of magnetism to make electric motors work is: A magnet has two different ends, or poles a north and a south pole. These poles behave like electric charges, like poles repel and unlike poles attract although magnets have no affect on still charges. The relationship between electricity and magnetism is that each phenomenon is that each generates a field. Electric fields can be pictured by thinking in terms of gravitational forces. Where, any two objects have a gravitational force one another. Any two electric charges have a force between them (either repelling, or attracting depending on polarity). These electric fiel...
There are many uses for magnets. One of the more interesting uses of magnets is how they are used to both suspend, and propel trains. In this day and age, there are not many vehicles that can match the performance of an airplane, in terms of being able to transport a large number of passengers in such a short amount of time. The average train has the ability to carry a large number of passengers, but is not as good when the need for speed arrives. Maglev trains are a solution to this problem, with the ability to run at speeds much higher than conventional trains, and transport just as many passengers.
A market economy is a society that is industrialized. For example, there are factories and workers that make goods. But a society does not need capitalism to be industrialized. A market economy is where there are people who compete. They try to get money by themselves and only for them. They are money greedy and the want it all. This is a goal and this is what a market economy focuses on. But even though society is industrialized, they have limits. They are controlled by the government. For example, Social Security is controlled by the government. When the government controls, institutions do not have many rights. For social security, there are qualifications and these qualifications are made by the government. But the poor face more problems than the rich. For example, the rich have more power and control the ways there
The magnetic susceptibility χ (=M/H) (FC and ZFC) as a function of temperature measured at low applied field (H=50 Oe) is presented in Fig.5. The molar susceptibility shows a monotonic increase upon cooling down to ~ 22 K, where a steeper increase is observed. Below this temperature a bifurcation between the ZFC and the FC curves is evident (see inset of Fig.5. On the other and above 22 K the reciprocal magnetic susceptibility (1/χ) as a function of temperature shows a linear trend (Fig. 5 right scale). In detail, above ca. 30 K, in the paramagnetic region, the Curie-Weiss law is strictly followed. By fitting the linear part of the 1/χ curve with 1/χ = (T-p)/C, in the 30-310 K temperature range, a Curie-Weiss temperature, p = -2.3 K, and the Curie constant, C = 1.30 cm3.K.mol-1, (µeff = 3.2 µB) were obtained. The small negative Curie-Weiss temperature indicates the presence weak antiferromagnetic exchangeinteraction between the Ni magnetic centres. Indeed, the χT curve (Fig. 6 left scale) shows a downward curvature, typical of systems with antiferromagnetic correlations and/or non-negligible spin-orbit coupling. The χT=1.31 cm3.K.mol-1 at 310 K undergoes a small and gradual decrease to 1.19 emu.K.mol-1 at 24.5 K. The Curie constant value, either obtained by1/χ linear fit or the χT product for T>>p is in reasonable agreement with the expected spin-only theoretical value for NiII in octahedral environment with S=1 spin state (C = 1 cm3.K.mol-1and µeff = 2.83 µB considering g = 2) for unquenched orbital moment C = 3.91 cm3.K.mol-1and µeff = 5.59 µB).
The development of superconductors has been a working progress for many years and some superconductors are already in use, but there is always room for improvement. In 1911, Dutch physicist Heike Kamerlingh Onnes first discovered superconductivity when he cooled mercury to 4 degrees K (-452.47º F / -269.15º C). At this temperature, mercury’s resistance to electricity seemed to disappear. Hence, it was necessary for Onnes to come within 4 degrees of the coldest temperature that is theoretically attainable to witness the phenomenon of superconductivity. Later, in 1933 Walter Meissner and Robert Ochsenfeld discovered that a superconducting material will repel a magnetic field. A magnet moving by a conductor induces currents in the conductor, which is the principle upon which the electric generator operates. However, in a superconductor the induced currents exactly mirror the field that would have otherwise penetrated the superconducting material - causing the magnet to be repulsed- known today as the “Meissner effect.” The Meissner effect is so strong that a magnet can actually be levitated over a superconductive material, which increases the use of superconductors. After many other superconducting elements, compounds, and theories related to superconductivity were developed or discovered a great breakthrough was made. In 1986, Alex Muller and Georg Bednorz invented a ceramic substance which superconducted at the highest temperature then known: 30 K (-243.15º C). This discovery was remarkable because ceramics are normally insulators – they do not conduct electricity well. Since their discovery the highest temperature for superconductivity to occur is 138 K (-130.15º C).
Temperature has a large effect on particles. Heat makes particles energized causing them to spread out and bounce around. Inversely the cold causes particles to clump together and become denser. These changes greatly F magnetic the state of substances and can also influence the strength of magnetic fields. This is because it can alter the flow of electrons through the magnet.
In today’s world science and technology has made human life difficult just because of its new inventions. Everyday many new technologies are been added to the list. People get addicted and they don’t know what they are giving up in return. However, these technologies are taking away the human’s ability to think quantitively. Defining human in today’s world means substituting technology for work and thinking that humans used to do. For instance, the ability to count, the memory to remember, the ability to learn through classrooms, and the ability to do things by hand.
The various types of magnets are used in countless facets in everyday life. Thousands of industries, including automotive, electronics, aerospace, craft, manufacturing, printing, therapeutic and mining utilise magnets so that their machineries, tools and equipment can properly function.