Abstract: A grinding wheel including: (a) an annular core body which includes a multiplicity of aggregate particles and a resin bond that holds said aggregate particles together; (b) an abrasive layer which is disposed radially outwardly of said annular core body and which includes a multiplicity of abrasive grains and a vitrified bond that holds said abrasive grains together; and (c) an impermeable coating which is formed of a synthetic resin, and which is disposed on said annular core body.

Abstract: A grinding wheel of segmental type including an inner cylindrical core portion, and an outer grinding portion consisting of a plurality of segments which have abrasive layers formed of abrasive grains bonded together with a glass bonding agent and which are bonded to an outer circumferential surface of the core portion with a synthetic resin layer interposed therebetween, wherein a linear thermal expansion coefficient ?seg (/° C.) of the segments and a linear thermal expansion coefficient ?cor (/° C.) of the core portion satisfy a formula |(?cor??seg)|?6×10?6.

Abstract: A grinding wheel including: (a) an annular core body which includes a multiplicity of aggregate particles and a resin bond that holds said aggregate particles together; (b) an abrasive layer which is disposed radially outwardly of said annular core body and which includes a multiplicity of abrasive grains and a vitrified bond that holds said abrasive grains together; and (c) an impermeable coating which is formed of a synthetic resin, and which is disposed on said annular core body.

Abstract: A grinding wheel of segmental type including an inner cylindrical core portion, and an outer grinding portion consisting of a plurality of segments which have abrasive layers formed of abrasive grains bonded together with a glass bonding agent and which are bonded to an outer circumferential surface of the core portion with a synthetic resin layer interposed therebetween, wherein a linear thermal expansion coefficient &agr;seg (° C.) of the segments and a linear thermal expansion coefficient &agr;cor (° C.) of the core portion satisfy a formula |(&agr;cor−&agr;seg)|≦6×10−6.

Abstract: A method of bonding an abrasive solid mass to a desired member with an adhesive, wherein the abrasive solid mass has a porous abrasive structure in which a multiplicity of abrasive grains are held together by a bonding agent. The method includes a sealing-film forming step of forming a sealing film on a surface of the abrasive solid mass, for preventing the adhesive from penetrating into pores formed in the porous abrasive structure.

Abstract: A catalytic converter includes a housing, a honeycomb heater fixed to inside the housing, and a catalytic element disposed downstream of the honeycomb heater. The honeycomb heater has a first honeycomb structure made of metal having a first partition wall having a plurality of first throughholes, and at least one electrode for electrifying the first honeycomb structure. The catalytic element fixed to inside the housing and disposed downstream of the honeycomb heater has a second honeycomb structure having a second partition wall having a plurality of second throughholes, and a catalytic compound loaded on the second honeycomb structure. A horizontal cross-section of the honeycomb structure is made smaller than that of the honeycomb structure. Further, a gap between an outflow end surface of the honeycomb structure and an inflow end surface of the honeycomb structure is made large.

Abstract: A honeycomb heater comprising a honeycomb structure and a catalyst layer supported on partition walls of the honeycomb structure. The honeycomb heater includes a first portion that is resistance adjusted such that the first portion is adapted to heat more quickly than a second portion of the honeycomb heater. The first portion includes at least an inlet end of the honeycomb that receives gas that flows therethrough. In addition, the first portion has an area along the gas inlet within a range of 5 to 50% of the sectional area of the gas inlet. The first portion may extend through the honeycomb structure and terminate before reaching the gas outlet of the heater. The partition walls of the first portion may have a different hydraulic diameter, different thickness or different cell density than the second portion of the honeycomb heater.

Abstract: A honeycomb heater includes a honeycomb structure having a periphery, a front end, and a back end, including a plurality of passages which are defined by partition walls and extend in an axial direction of the honeycomb structure, the honeycomb structure being electrically conductive, whereby fluid flows through the passages from the front end to the back end; and a device for applying electric current to the honeycomb structure so as to generate heat; wherein at least one gap for obstructing electric current extends through the partition walls from the back end toward the front end but does not reach the front end so that, upon applying electric current to the honeycomb structure, a front region of the honeycomb structure heats more quickly than a back region of the honeycomb structure thereby a catalyst composition loaded onto the front region is activated earlier. Slit may extend between the front end and the back end.

Abstract: A honeycomb heater including a honeycomb structure, two electrodes and a plurality of slits extending through the honeycomb structure. The slits are provided to elongate a current flow path through the honeycomb structure and to define a plurality of first regions of partition walls and at least one second region of partition walls. The first regions are locally quickly heated with respect to at least one second region upon electrification of the honeycomb structure, and the first regions are spaced apart from each other. In addition, the first regions in total extend over an area 5 to 50% of a total cross-sectional area of the honeycomb structure. Alternatively, the honeycomb structure may include at least one first region and a plurality of second regions, the second regions being spaced apart by the at least one first region.

Abstract: A honeycomb heater including a honeycomb structure which is made of a conductive material and which has a number of passages substantially parallel to a gas flow direction partitioned by partition walls and which has respective providing a gas inlet and a gas outlet, and at least two electrodes for electrification provided on the honeycomb structure. The honeycomb heater is characterized in that besides the passages, orifices which have a larger hydraulic diameter than the passages and which narrow a current flow path are formed at predetermined positions of the honeycomb structure to adjust resistance, whereby a specific region of the honeycomb heater is locally heated more quickly as compared with other regions at the time of the electrification.

Abstract: A heater unit including a honeycomb heater, a metallic casing for holding the honeycomb heater, and a gas flow-controlling means for controlling flow of exhaust gas through the heater unit, such that about 2 to 20% of the total amount of exhaust gas flows outside the honeycomb heater, between the honeycomb heater and the metallic casing. The honeycomb heater may be attached inside the metallic casing via several appropriate devices including supporting, buffer and connecting devices.

Abstract: A heating element for heating fluid flowing therethrough, including an electrically conductive honeycomb structure, electrodes electrically connected to the honeycomb structure for applying an electric current to the honeycomb structure, wherein the honeycomb structure has a front region which is adapted to heat more quickly than a back region of the honeycomb structure. To this end, the honeycomb structure may include at least one gap for obstructing electric current flow, the gap extending through the partition walls and terminating before reaching the front end of the honeycomb structure. Alternatively, the front region may be heated more quickly than the back region by providing at least one depression formed the back end of the honeycomb structure, such that the front region extends from a terminating end of the depression toward the front end of the honeycomb structure. A catalytic converter incorporating the heating element is also provided.

Abstract: A heater unit comprising (1) a honeycomb heater comprising (a) a metallic honeycomb structure having a large number of passages parallel to the direction of a gas flowing through the heater unit and (b) at least one electrode for electrification of the honeycomb structure, attached to the honeycomb structure, and (2) a metallic casing for holding the honeycomb heater (1) therein via at least one metallic supporting member, in which heater unit an insulation portion is provided at least either at the connection area where the honeycomb heater and the supporting member are connected or at the connection area where the supporting member and the casing are connected, and the supporting member has such a structure as to be able to absorb the displacement of the honeycomb heater which appears in a direction substantially perpendicular to said gas flow direction, and has a function of fixing the honeycomb heater against its displacement which appears in the gas flow direction.

Abstract: A heater unit includes a honeycomb heater having a resistance adjusting component and a casing for holding the heater, wherein at least part of the side of the heater is covered with protective member(s) via an inorganic adhesive and the resulting heater is held in said casing. This heater unit has a highly integral structure and can prevent short circuiting even under the severe driving conditions of automobiles and allows the resistance adjusting component (e.g. slits) to have reliable isolation from each other.

Abstract: A honeycomb heater has an integrated honeycomb structure obtained by connecting in series, via conductive plates, a plurality of honeycomb structure elements each having a large number of passages and each generating heat when electrified. At least two electrodes are provided on the integrated honeycomb structure for enabling the electrical heating thereof.

Abstract: A heating element for heating fluid flowing therethrough includes: a honeycomb structure having a periphery and two ends, including a plurality of passages which are defined by partition walls and extend in an axial direction between the ends, the honeycomb structure being composed of an electrically conductive material; and a pair of electrodes for applying electric current to the honeycomb structure so as to generate heat; wherein a maximum length of linear portions of the partition walls is up to 10 mm as viewed in a cross-section of the honeycomb structure taken perpendicular to the axial direction, and a number of the passages in one square inch ranges from 50 to 800 as viewed in the cross-section of the honeycomb structure, thereby insuring improved thermal shock resistance and purification efficiency. The partition walls are less prone to deformation and crack formation due to thermal stress.

Abstract: A catalyst for exhaust gas purification has at least one monolith carrier, at least one first catalyst layer having a three-way catalytic activity, provided on the carrier, and a second catalyst layer having a hydrocarbon purification activity, provided on the first catalyst layer. In a gasoline engine automobile provided with the above catalyst for exhaust gas purification in the exhaust gas system, the hydrocarbons present in the exhaust gas can be converted at a high efficiency by introducing secondary air into the exhaust gas in front of the catalyst to make the exhaust gas lean, at the engine start when a large amount of unburnt hydrocarbons are present in the exhaust gas. Further, the engine warm-up property of the automobile can be improved by the heat generated by the catalytic reaction of the hydrocarbons. The catalyst further exhibits a three-way catalytic activity even during the steady state engine operation after warm-up.

Abstract: A resistance-adjusting-type heater including a honeycomb structure having a large number of passages and at least two electrodes provided on the honeycomb structure for energizing the honeycomb structure. The honeycomb structure has a slit or slits which form a predetermined angle to the partition walls of the honeycomb structure so as to enable adjustment of resistance between the electrodes, so that gas flowing through the passages of the honeycomb structure is heated.

Abstract: A honeycomb monolith heater including a honeycomb structure having a plurality of passages of square or rectangular cross-sectional shape and a plurality of electrode plates fixed to the outer wall of the honeycomb structure, in which the electrode plates are arranged so that the angle formed by the electrode plates and the passage walls is an acute angle. A honeycomb monolith heater assures uniform heat generation and which has improved mechanical properties.

Abstract: A resistance adjusting type heater including a honeycomb structure, electrodes provided on the honeycomb structure, and slits as a resistance adjusting device provided between the electrodes, a sealing device for sealing a heat-non-generating portion of the honeycomb structure, wherein a gas is introduced into the passages of the heat-generating portion of the honeycomb structure and is heated. With this heater, the entirety of the exhaust gas introduced into the heater can be heated rapidly thereby ensuring excellent purification efficiency.