Abstract: A ferrofluid rotary-shaft seal apparatus of extended seal life, particularly adapted for use as an exclusion seal with a computer-disc-drive spindle, which seal apparatus comprises: an annular permanent magnet; first and second pole pieces, one end of which pole pieces extends into a close, noncontacting relationship with the surface of the rotary shaft to form a gap therebetween; ferrofluid in the gap to form at least one O-ring seal; and a heat-conductive sheet material in a close, heat-conducting relationship with at least one pole piece, to aid in removing heat from the ferrofluid in the gap, thereby extending the seal-apparatus life in use.

Abstract: A stable liquid composition which comprises a colloidal dispersion of finely-divided particles in a liquid silicone-oil carrier and a dispersing amount of a surfactant, which surfactant comprises a silicone-oil surfactant containing a functional group which forms a chemical bond with the surface of the particles and a tail group which is soluble in the silicone-oil carrier, to provide a stable ferrofluid composition.

Abstract: The circumference of a crystal rod is monitored and controlled during the rod growing process by providing relative rotation between the growing crystal rod and a melt of the crystal material as the rod is being pulled from the melt according to the Czochralski method, and by using a radiation-sensitive control system for adjusting growth conditions of the rod in response to variations in a radiation signal which is indicative of the circumferential dimension of the rod. An electronic circuit integrates the radiation signal over each complete rotation of the rod, thereby eliminating unnecessary adjustment of the growth conditions in response to diametric variations of the rod which recur regularly in each rotation.

Abstract: An apparatus for and a method of handling grown crystal ingots from a crystal-growing furnace, which apparatus and method include: lifting and moving an upper crystal chamber with the crystal supported therein to one side of the furnace; and gently lowering the crystal into a lower crystal chamber positioned beneath the upper crystal chamber and on a wheeled vehicle, which permits ease in removal and transport of hot heavy crystals with minimum damage or fracture.

Abstract: A ferrofluid rotary-shaft seal apparatus of extended seal life particularly adapted for use as an exclusion seal with a computer-disc-drive spindle, which seal apparatus comprises: an annular permanent magnet; first and second pole pieces of unequal length at the one end, and which one end of each pole piece extends into a close, noncontacting relationship with the surface of the shaft, to form a small-gap width and a large-gap width between the one end of the pole piece and the surface of the shaft; and a ferrofluid in the small- and large-gap widths to form a ferrofluid O-ring seal at each gap width, whereby, during rotation of the shaft, the ferrofluid at the small-gap width evaporates and forms an air gap, while the ferrofluid at the large-gap width provides extended seal life.

Abstract: A stable ferrofluid composition which comprises a colloidal dispersion of finely-divided magnetic particles in a liquid, low-pressure, polyphenyl ether carrier and a dispersing amount of a surfactant, which surfactant comprises a polyphenyl ether surfactant containing a functional group, such as an acidic group, and an aromatic tail group which is soluble in the polyphenyl ether carrier, to provide a stable ferrofluid composition.

Abstract: A seal apparatus to prevent the escape of a ferrofluid from a multiple-stage ferrofluid rotary seal about a shaft during axial movement of the shaft element, the seal apparatus comprising a pressure ring element against one facing wall of the rotary seal, a scraper ring element positioned within the pressure ring element, the scraper ring having a sharp forward edge adapted to contact the exterior surface of the shaft to prevent the escape of ferrofluid from the seal, and tension means to force inwardly the pressure ring and scraper ring toward the seal means.

Abstract: A crystal puller uses a chain and sprocket in the pulling head for vertical support of the growing crystal. Replacement of the chain is effectuated by providing an aperture in the top of the pulling head aligned with the sprocket. Replacement chain fed through the aperture can be directed to a storage area initially then by reverse sprocket motion lowered to commence a crystal growth cycle.

Abstract: A linear drive-shaft sealing apparatus particularly useful in removing crystals from a melt solution of an evacuated chamber, which sealing apparatus comprises a first input drive shaft and a second output drive shaft, both shafts adapted for linear movement, a cylindrical element disposed between the input and output shafts and adapted for rotary movement, a housing surrounding the cylindrical element, and a multistage, magnetic seal apparatus which provides a magnetic seal between the housing and the cylindrical element.

Abstract: A self-activating ferrofluid-seal apparatus for a memory-disc-drive shaft, which seal apparatus comprises a ring magnet and a pair of pole pieces which form a cavity therebetween, a closed loop of a plastic tubular container with ferrofluid positioned within the cavity, and a penetration clamp to penetrate the plastic container prior to installation of the shaft element.

Abstract: A self-activating seal is formed by inserting a magnetically permeable shaft into a module which comprises: a magnet, two pole pieces and a magnetic fluid. The module is so constructed that the magnet and pole pieces form a cavity for storing the magnetic fluid until the shaft or similar element is inserted. Upon insertion of the shaft, the magnetic field is altered and the flux path diverted to the small gaps separating the pole pieces and the shaft. The magnetic fluid is drawn to the gas to form hermetic seals.

Abstract: A ferrofluid centrifugal seal and method of sealing a rotatable shaft, wherein ferrofluid is retained in an O-ring-seal form at static and low speeds and is moved to a barrier seal in a passageway at high speeds.

Abstract: A seal for rotatable shafts utilizes a ferrofluid as a sealant and lubricant. As a sealant, the ferrofluid acts to exclude particulate matter from passing through the seal area contaminating internal mechanism elements, while as a lubricant, the ferrofluid forms a film between the shaft and the elastomer-material seal element; thus, cooling and lubricating the contact interface and acting to extend the life of the related components. The seal assembly has permanent magnetic elements which create a magnetic-field gradient, causing magnetic-field maxima at points immediately surrounding the contact point between the seal-elastomer material and the shaft. The ferrofluid is entrained magnetically within the interface region; thus, insuring continual lubrication of the contacting surfaces, while further, the entraining forces prevent leakage of the ferrofluid from the region.

Abstract: A viscous-fluid inertia damper, which damper comprises a housing composed of a nonferromagnetic material and having a chamber therein, a seismic mass containing a permanent magnet disposed in the housing chamber and in a closely spaced-apart relationship with the internal wall surface of the chamber, means to couple the housing to a dynamic element whose energy is to be dampened, and a ferrofluid of selected viscosity in the remaining volume of the chamber, the ferrofluid distributed generally uniformly in the volume, the magnetic saturation of the ferrofluid by the magnetic field of the permanent magnetic levitating the seismic mass in the damper, and the viscosity of the ferrofluid in the magnetic field providing a means to dissipate energy from the dynamic system through viscous shear forces in the ferrofluid disposed between the wall surface of the chamber and the seismic mass.

Abstract: A roller assembly utilizes a ferrofluid as a lubricant (ferrolubricant). Integral structural portions of the assembly are made to have magnetic portions which create their own magnetic field gradient causing magnetic field maxima at points immediately surrounding the contact point between a particular roller element and its raceway. This in turn entrains the ferrolubricant around the contact point thus ensuring continued lubrication of contacting surfaces. Further, the entraining action prevents leakage of the ferrolubricant from the assembly.